Just as a counterpoint: the Nevada Gaming Commission has plenty of time and money to sift through the source code of every gaming device that gets deployed in NV.
Compared to any car ECU and related software, gaming machine software is rather simple. Not exactly trivial, but much simpler, and the state can afford to set rather arbitrary behavioural restrictions.
Similar restrictions would severely cripple innovation in cars. Just consider Tesla's autopilot software.
If I write the software for those devices in ASM, do/can they still look through it?
Is there some kind of formal engineering practice they require manufacturers to adhere to?
How are their staff qualified to read the vast variety of languages out there?
I cite these as immediate, obvious roadblocks to verification, regulation, because they're easy and many PLs are something that the vast majority of the software industry are not used to.
Do we have specific evidence that they actually do sift through the source code? They demand its submission, but how do we know they actually do anything with it? I'm asking this as a serious question.
It doesn't really matter if they sift through every one so long as they have them on record. If there's ever an allegation of misconduct, the code can be examined in full by any large variety of experts.
Similar restrictions would severely cripple innovation in cars. Just consider Tesla's autopilot software.