You are correct but I think previous comment hung on specific word you used: "semi-autonomous". What that would mean is a system that still requires attention / supervision. What I believe you meant is an AV that still has human controls but is capable of unsupervised driving.

If you aren't familiar with SAE AV levels, check them out. It is a common refrain that L3 AVs are a SUPER bad idea because they would be 99.9% perfect at driving but could still mess up so 'drivers' of them would become too trusting and minimally attentive which would cause accidents.

The common thing is that L3 needs to be skipped entirely so a car should either be L2 and wouldn't be good enough to drive entirely on its own for long periods (lane assist, low speed traffic jam chauffeur, etc) or L4+ where the car can drive on its own but if conditions degrade where it can't continue it is capable of finding a safe spot to stop rather than aborting in the middle of driving suddenly.

The controls vs no controls isn't really an argument. Like you said, it will basically be fine either way if the system is sufficiently advanced especially if autonomy can't be disengaged while moving.

Failing to see or refusing to look is not evidence that something is not there.

The human part is the failure point IMO. The problem is when the human is not in the back seat, but overriding the car.

A car with no wheel, and the human in the back, is not different to one with a wheel and the human in the back, it is when the human is sat in the front only partially controlling the vehicle. That is when it is less safe.

So 2 situations, one where the human can sit anywhere and the car is just as safe, or one where the car is less safe if the human sits in one of the seats.

One of those situations is less safe than the other.

I think the argument for autonomous is that human intervention is, generally, wrongly rather than rightly.

At this point, I won't agree or disagree, but it's getting more interesting all the time.