I do agree there is some nuance, but it really saddens me that so many comments in this thread are supportive of a form of driving that, while very common, is unsafe for themselves and others. It's a form of normalisation of deviance and I'm sure it costs far more lives than teslas dodgy "autopilot" (even if that too should not be road legal).
People sometimes fill the gap in front of me, and if they're particularly unsafe about my induced following distance I flash my lights, flip them off, and back off. In a typical 30 mile drive in one of those metros it costs on the order of tens of seconds. People usually aren't that aggressive about filling gaps until they have something to gain, so the frequency of people causing you to slow down winds up being pretty low.
So no, it's not the case that people trailing too closely is the problem. It's the case of the Tesla requiring, without good reason, the car behind them to brake hard to avoid the collision. This is dangerous and (usually) illegal.