The maker and or operator of a self driving car can be held accountable depending on the specifics. IMO, we have this odd social expectation that humans killing people with cars or pollution is basically acceptable and nothing else really gets that pass.

IMO, killing someone with a car or a gun is a direct equivalent.

It's equivalent, yes. When someone recklessly kills someone with a car, it's called vehicular manslaughter and they are punished for it. It's not considered acceptable.

Blurring the lines of accountability is an anti-feature. The killer feature for humans is that we can be held accountable.

That’s assuming it’s prosecuted which is rare. However, just looking at the laws directly you notice the odd exclusion.

In California for example vehicular manslaughter is specifically excluded from involuntary manslaughter and carries a lower penalty. It is also frequently just a misdemeanor.