You believe signatures by engineers matter.
That is your belief, but I've never seen that belief backed by fact.
Most open source software disowns liability in CAPS in the license. Yet somehow FOSS like Linux gets used for safety critical infrastructure.
Microsoft would love certification requirements for engineers - that would kill open source to their conpetitive benefit.
Do you honestly think if we required Microsoft Certified Professionals to sign the internals of Microsoft OS then Windows would be more secure or reliable?
The bigger issue is that signatures and criminal consequences hardly matter across jurisdictions.
The capitalist issue is that businesses want scapegoats when things go wrong. That would be the outcome of signatures: engineers as fallboys for systemic failures across organisations.
Note how often pilots are blamed for accidents due to the design of planes.
It is just an idealistic belief based on feelies that software certification would achieve the goals you imagine it would.
Signatures are an anachronism: from an alien past.
International business uses different mechanisms for safety.
Our world is intertwined complexity. You somehow think that the buck should stop at engineers?
If engineers signed off on everything then we'd have no more disasters like New Orleans floods?
Who signed what for the Grenfell towers tragedy? Which engineers were reprimanded? Did they decide that more signatures would help prevent future disasters?