You can call me an apologist but I believe there is a "cause and effect" in many of these rage situations. So what caused a nice quiet person to behave badly and so far from their norm?

I think most "ragers" are nice level-headed people 99.9% of the time. Most normal people get angry or upset when they have to suddenly deal with ab-normal conditions, illegal behavior, breaking the rules, like a distracted driver risking the (usually) normal person's safety or intruding into their space. Its real. Nobody is immune to reacting poorly when they are thrust into situations they are not prepared for.

Is dealing with people reading (texting) instead of driving the new norm? The law says no and I totally agree. I'll continue to give my horn a toot when my space is being intruded by a self-centered, PIA or worse.

The Edmonton situation was extreme and is not road-rage, that was attempted murder. That fellow has a history of violence.