Outside of a few specific places if we're talking car dominated societies this is demonstrably untrue, the point is to make it faster for people in cars, maybe a bit safer and the rest is at best an afterthought. If you wanted to make things safer for everybody, including people in cars, you'd see a lot less wide roads, more obstacles and such.

If people are crashing over new enforcement policy, the moral choice for a city to make is to determine what will save the most lives. It's of no consequence to the city if they look at who caused the accident and they say "Guy in the back drove too close, lol, not our fault. Our laws are clear."

Again this is only looking at this in the context of cars and nothing else. What kills people when cars run red lights is sometimes cars, but most often people not in cars. And the latter is how the entire system is resolved and is what you're defending here - what's the other option? You can't actually enforce running red lights anymore?

Yes, the trailing driver should leave space, but its the job of a traffic engineer to account for human variability and advise ways to minimize risk despite the tendency of some people to acy irrationally

Should be, sure, but that entire field basically runs on the fiction of the ever competent driver who doesn't fuck up. And anytime you try to change this people get up in arms because obviously they're the one person who doesn't make mistakes and as such would like to not be impeded