Send a low level engineer to prison, of course.

That's actually not as wild as you think, because that's what happens when a building or bridge falls. The contractor that built the bridge, just like the company that designed it, the agency responsible for inspections and maintenance, etc, is also liable for damages, including prison if it's deemed so by the courts.

Of course, software engineers get treated with kid's gloves, otherwise, everyone just freaks out and cries and cries, because their robotic utopia dreams are meaningless nonsense.

> We send people to prison when they make those kinds of mistakes, what do we do when machine learning models kill while functioning entirely normally?

Assess a massive fine. Money is lifeblood of a corpo.