Slot machine manufacturers don't have anything to hide, as there is nothing malicious about their software - it's programmed to mathematically make the players lose money most of the time, but everyone already knows that. Thus they have no incentive to fight against their firmware being open for regulator scrutiny.
Automotive manufacturers, on the other hand, have very good incentives for their firmware not being open for regulator scrutiny, as the recent events have shown...
Huh, what? The commenter is asking why one industry is open to regulator scrutiny and the other isn't.
My reply covers why lobbyists from one industry might have incentives for not being open to scrutiny, while lobbyists from the other industry might not.
I'm not answering literally the question "why is it acceptable..." because that's not the real issue at play here.
Automotive manufacturers, on the other hand, have very good incentives for their firmware not being open for regulator scrutiny, as the recent events have shown...