I’m sure most of HackerNews has some handwavy easy ideas for how to improve it. But as you can imagine there is a good reason the system is built on hard guarantees, not obvious shortcuts.

If your simple exit sign fails, it isn’t going to cause two trains carrying potentially thousands of passengers to collide head-on. If that happens it’s a major disaster that’ll be world news and there’s going to be questions to be answered, like why the safety wasn’t guaranteed.

If this was the case they'd just be waiting until the second bulb burnt out as well and then we're back to square one.