Is that really a large subculture, or is that mostly car rental places cycling vehicles through their fleet?

The rental companies typically buy vehicles from the manufacturer at such a volume discount, that they're able to flip them onto the used market a few years later and come out even with taxes benefits factored in.

There are also private and corporate leases. In the UK at least 20-30% of new car sales are leases (it's a tax efficient way to get a new car, particularly EVs), and these usually run for about 3 years, after which they're sold off at trade auction.

Do those same cars have 0 problems with them and not require any scheduled maintenance in those 13 years?

You are talking about the auto market like Japan didn't come in and devastate Detroit. No problems means things about TCO to 16 years and how that plays out.

Mid tier Android makers that couldn't secure chipset support beyond 3 years began to realize they have to exit the market a couple years ago, a guaranteed outcome of Apple fixing their story long enough for resale values to impact purchase decisions.