>>If I were to guess why - if we did, people would either not work on experimental systems or would gold-plate the safety features way beyond what was reasonable. That sounds nice if you don't think about it too hard but in practice it would shave % off how much we produce in goods and services for no reason.

Certified engineers absolutely can and do go to prison for structural mistakes in their projects, especially if those mistakes lead to loss of human life, but sometimes even without it - chief engineer of what was the tallest human-made structure on Earth(radio mast near Warsaw) went to jail for 2 years after the mast collapsed due incorrect design of the support structures.

Does it stop people from becoming engineers or from embarking on difficult projects? Of course not. If anything, it shows that maybe programmers working on projects like the autonomous cars should not only be certified the same way engineers are, but also held liable for what they do.