Think about how many hoopties are already on the road with broken lights, bad alignment, bald tires, no ABS/ESP/TC, dangerous suspension geometry like semi trailing arms, no oil changes, etc. Why don’t we start handwringing about poor vehicle maintenance?

If it is a self-driving software update that the manufacturer could push but chooses not to (or could trivially port), I think it becomes much more difficult liability-wise and legally for them. I'm not saying that is the correct way, but I think it is how it would work in practice.

We do in some places. Where I live (Iowa) we don't - but most people take better care of their car than that so it is pointless. As a kid I remember parts of MN requiring inspection and a few years latter dropping it when they realized nearly every car was passing so there was no point (this was emissions only not safety). In Texas there are regular inspections - but if you go to border towns you see a lot of those poorly maintained cars on the road (despite the inspection) and so people see more need for them and they keep them.

See this is why people in iowa don't deserve a senator

I mean that's basically how every car with half-assed barely-functional auto lane keeping sold in the last 7 years has worked.

i think self-driving changes the calculus

Relying on crappy lane keeping and crappy self driving are equally dangerous. If poor software drives you off the road, why does it matter what the feature was named?

I don't disagree on the practical level, but I think that optically it is significantly different.

Anything before L4 is "driver assist", which means at the end of the day, the buck stops at the driver. Anything beyond L4, the car itself drives without requiring supervision, which makes a big difference. It's your responsibility to use lane assist in a reasonable way, it's not your responsibility to control how an L4 drives anymore. That's the point of self-driving, the "self" is responsible.