I think a big part of it is that driving is inherently dangerous (you’re in a metal box going much faster than you’re capabale of going yourself, your health and finances are at stake) and frustrating (waiting in traffic, people making mistakes).
All those things put people on edge and cause them to act out
I disagree, I think most of the time it’s pretty easy to read someone’s intention (since there are only limited choices and there are ways of communicating like indicators). But I think the fact that you’re not face to face with the person and are much more likely not to face consequences for your actions definitely plays into it