As long as they are still sending out flyers with stuff you buy you are okay. Also, if you already knew the price range of your regularly shopped goods, you know something is off. Superstore is already using digital tags. And you can just pull out your phone and take pictures.
Lastly, it should be put into law so you can't increase price during the day. Going down is fine, but no going down and then going up again for peak hour. Stores can set whatever price they want to sell before opening. (for those non-regulated things)
that's entirely not possible even if she is driving a F1 car since it takes time and distance to get up to that speed. if the attorney can fetch her phone location tracking record, can roughly know how fast she usually travel on a car for the days before that accident.