Don't take this as a criticism, but do you own a home?

How would changing property values be accounted for, and how often is the appraisal done, and who pays for that? Can a landlord sell his rentals to someone else while they are rentals? If no, why not? What incentive does a landlord have to keep a property nice and safe if x% is no longer theirs? If the rent-to-owner decides they want to move or not buy the house, what happens to the money? Is any given to the landlord? Why can't the landlord increase rent to drive out a tenant? If a new sewer line needs to be run, and it's $10k, how is the cost split? How are property taxes dealt with if the unit is owned by multiple parties? If a homeowner owns 51% of the property and someone is injured on the property, who's insurance pays?

I get there is a lot to dislike about slumlord type landlords, but property and home ownership isn't like buying a toaster. There are a ton of laws and rules and responsibilities that clearly defined parties still have court cases over. There is financial risk in property ownership, and your proposal seems to be having private citizens, even if "rich" by your definition, and it is the government dictating private use of their property.

There are positive aspects to renting, which you don't seem to consider. I tried to sell my house for over a year, but foreclosures had driven down property prices so much for a time, I literally couldn't afford to give my house away for below market value and still have any money left to put on a new house. If I was a renter, I could just say I'm done here and go off and do whatever. If something breaks, there's someone who is supposed to fix it, no cost or effort to you. You don't need to worry about taxes and setting aside money for maintenance or hire contractors.

I want everyone to have a home, and I hate scumbugs and corporate ownership of residential property, but many of these people do serve important purposes, and many people would not have a place to live if property owners didn't rent out access to those properties.

Again, I'm not a landlord because of many of these things, but I do own property and wouldn't like something like this. It is a very complicated issue and this just comes off as someone who's never had to fight the local zoning board, deal with a utility screwing around with you, or having messed up property records having the government trying to make you pay taxes you don't owe say property owners have it made. It took me 8 years, 3 title insurance companies, and a judge to get my property records corrected after my divorce.

Expanding construction of affordable housing people would want to live in and expanding housing subsidies and just in general providing adequate social safety nets will get people in homes. Giving people with no means to maintain a home is not a benefit, it's just another huge thing that brings a pile of never-ending expenses.

It would actually be easier to just set massive taxes for anyone that owns more than 2 houses. I don't begrudge anyone who owns a house and a vacation house but fuck anyone who just owns rental properties, and if you can afford to buy a third house then you can afford to pay a ton more in taxes to keep it. The more houses you own the higher the taxes go, just make it untenable for people to own rental properties and the rest sorts itself out.

The renter pays extra and receives part ownership. So the owner receives this extra money and... just has to keep the money on hand in case the renter leaves years down the road?

The whole thing is a legal nightmare. Owners would just sell. And who would buy? Corporate landlords who have lawyers who can cut through all this confusion.

Yeah no. Make it illegal for companies to own residential properties. Sure they can build em and sell em within a given time frame after building or renovating them, but within 5 years tops individuals should own the property.

Progressive tax rates the more properties you rent out.

Renting is one of the main causes of permanent poverty. I don't give a flying fuck about your "investment opportunities". You're getting cash while others are losing money.

I think it would be more useful to dramatically increase taxes on unoccupied or AirBnB properties. Increase penalties on slumlord behavior. Similar things to gently (or not so gently) discourage people from hoarding residential real estate.

Otherwise, if someone was renting my house and they wanted to buy it at $100/month, it would probably take more than 800 years to buy (if I could afford to get it into shape to maximize the appraisal).

Paying such a small percentage would mean it takes a lifetime to be able to afford the house. If we take the median home value($360,681), $100 a month would take 300 years to own the house. That doesn't even account for inflation and an increase in home value. You would just be pissing away money that could be better used otherwise. If you increased the payments, you would be better off saving or investing to buy a home than trying to buy the one you were renting.

How about we just ban companies from owning rental properties or homes longer than one year and nobody can rent out more than one home.

My only point here would be I'd switch from actual ownership to more of an "option" ownership option. Similar to stock options, every time you pay rent you get more of the "options". When a sale event happens, you can exercise your options and have a chance to buy the property there. Or, if they want to exercise now they can and they'd own shares of the building there. Once it tips to 50% then the shareholders own it.

Every year you receive more options, you are under no obligation to exercise them. However, every year you rent you receive more options. If you leave and you did exercise your options you get the value you put in back, but if you didn't the options go back into the pool.

I think this is similar to co-ops in large cities, where there is a contract that the owners can start owning the building themselves over time.

What happens to people who rent out an apartment in the house they are living in? This is not uncommon, where I live. Grandma lives in a small separate apartment in the house, she dies, the apartment is rented out. Sometimes a child moves in later or the parents move in and a child takes over the house.
If these people risk losing a part of the house by letting someone else rent it, my guess is that they would just stop renting it in order to be able to leave the whole house to their children. Which would leave even less homes on the renting market and a bigger share to big corporations.

This is a plan called "Rent to Own". It's been a thing for decades now.

https://www.investopedia.com/updates/rent-to-own-homes/

OK, then I choose not to rent. You can go buy a house or rent or live on the street.

Now what?

I think an easier solution would be to expand section 8. The government should have tons of housing units built, and then families can "pay them off" with section 8 funding. Right now section 8 money just goes to slumlords. Instead that money could go to the people who actually need it. This would increase housing supply, so prices would come back down, plus allow people to build equity and ownership in their home allowing them to start raising themselves out of poverty.

Well in Germany there is the "Vorkaufsrecht" for the renter.

If I would sell my flat, the renter would have the option to buy it for the negotiated price. Not any imaginary price. There has to be a notarized sales contract which triggers the "Vorkaufsrecht".

The renter has the option to buy the house / flat at the established market price.

Unless you have strong rent control, expect proportionate increase in rent for any tenant who exercises that option.

Oh, you have $100/mo extra to spend burdening my equity? Your rent just went up by $200.

Not everyone who rents a house to live in wants to buy a house. Not everyone who rents a house to other people wants to sell a house.

If you reduce the ability for owners to make self-optimal choices with their property, then the property will be less valuable to them.

This means that in order for property to be as attractive an investment, they will have to raise rents.

Whenever you coerce people in a market, you make the market less efficient, which hurts everybody.

theres a current, common thing called something like buying/selling "on contract" that provides for a lot of the methods youve outlined