Normal wear and tear isn't the renter's problem in any way, shape, or form

Which is why I said it's a warranty issue.

and that includes dings and scratches on the paint, wheels, glass, and interior, simply from everyday use and being exposed to the elements.

We're going around in circles here: dings and scratches are not caused by normal use.

already pay over $500

rental companies, like every other company, are charging more and more for less and less

The price of the rental and the responsibility of the renter are different problems. If you think you can do it for cheaper, give it a shot. You can list your car on Turo and make a fortune undercutting these terrible companies.

I've never even had a car payment that high.

There's a myriad of expenses in rental that are not incurred by simply owning a personal vehicle (you've already listed a bunch of them), and a profit margin on top, so that makes a ton of sense.

What exactly are they doing with that money if the customers are the ones being charged for issues that aren't even getting fixed?

What makes you think they're not being fixed? Even if they're not, those issues decrease the resale value of the vehicle.