Probably because unlike paying for the service, we don't feel how it takes our money from us.
A psychological trick that works so great that it made a lot of services exist in the first place like the whole of YouTube. And now we're kinda addicted to those too.
I know I just thought the free trial would be more accurate.
I haven't thought about sales taxes, i guess you do pay more taxes if you count those.
Although not really similar to a subscription in that case.