You don’t pay for gas? Oil changes? New tires? Air filters?

I think you and I may be a rarity. Most people seem to value having new vehicles, and I don't say that dismissively- there's definitely something to be said for modern safety features as vehicles continue to grow bigger and heavier.

Do they run on air?

How much liability coverage are you getting for ~ $100/month? In other words if you injure or kill someone with your vehicle how much of that cost will be covered by your insurance company? With Waymo the answer is "not my problem".

Most people spend more per year on gas than you claim is your total cost of ownership. Sure, cars are cheap if you never drive them.

Your used cars are only so cheap because most people don't buy old used cars. If they did as you suggest, then it would no longer be such a good deal.

Insurance and parking tend to be expensive in expensive cities

If you want to go some distance you're always paying something to do it - you can't therefore assume all means of going a distance cost the same and that factor can be ignored, though. A plane, train, bus, car, and taxi are all going to have different cost efficiencies (some more different than others) of going on a given type of trip. From a different perspective, they all require purchase, maintenance, licensing, and registration as well - but those are still part of TCO because it's part of the total cost. If you remove them for being the same type of cost rather than the same actual cost then you wouldn't really end up with much going into TCO even though the total cost of each is wildly different.

In general, you're almost certainly no longer on the path to calculating anything that should be called TCO once you've started removing costs associated with using the item. Apart from that, you're probably not on your way to a very meaningful cost comparison either.

As an American I would also like to know... My actual expenses for my low end luxury car are nowhere near that high, and I live in CA which has massively inflated car expenses in practically all fronts.

Registration: $600/year

Insurance: $1,500/year

Gas: ~$2,700/year (15,000 miles @ 30mpg @ $5.50/gal)

Loan: ~$3,500/year if I had borrowed the entire price of the car on a 60 month loan and then kept the car for 15 years as the GP stated

Maintenance: Certainly less than $1,000/year, much less in most years.

And in some states registration and insurance could literally be a third of what I pay. Gas could easily be half. I can't imagine anyone is paying $12,000/year for any non-luxury vehicle.