Hell, even if governments are squeamish about requiring code to be fully open and public, they can still require the manufacturers to privately submit to the government all code that powers public infrastructure (like trains), to be made available to any relevant party upon request.
> can still require the manufacturers to privately submit to the government all code
I wonder if companies purchasing trains could put code disclosure in the purchase contract? I wonder if, in aggregate, train purchasers or car purchasers could fund an independent code storage vault and pay a small premium to fund that code vault organization?
In other words, if purchasers wanted this and valued this, they would demand it in purchase contracts and fund it.
then you just need to bribe the code reviewer(s).
open source is still the better answer, good luck bribing every member of the public who could potentially read public code.