In fact, new safety regs are often suggested by rail companies, who observe previously-unexpected situations IRL (despite the best attempts to nail these down in advance).

You're enjoying tossing around a lot of "What if"s, out of ignorance, but modern transit safety is not based on some dude sitting around and thinking up rules for funsies. It's a highly intensive engineering process, with multiple layers of cross-checking.

And then millions of us get behind the wheel, and there's nothing anyone can do about decisions made by each of them. Car safety is based on the hope people fear getting tickets, and some soft design aids.