You are right on both points. However, not many people, in this state at least, understand the concept of the zipper. That leads to a lot of irritated people. Furthermore, often the speed of traffic will drop 10-15 mph after the merge; some people intentionally drive that way. I will stay in whatever lane everyone else is in, even though I know it's wrong; by doing like everyone else, there's a lot less frustration. I tend to leave a gap in front of me big enough for another vehicle to drop into, any time that I'm driving. Right or wrong, I simply don't have time for an accident. That often causes the driver behind me to ride my bumper, even though I maintain the same speed as the vehicle in front of me.
Construction zones are different. I wish that they would enforce that "Fines double" on people who will speed up to get to the front of the line after everyone else has merged.
This incident has caused me to rethink my driving habits. I've taken some red tape and put an "X" on the horn button of both pickups. People are triggered too easily today. Furthermore, there could have been a reason he'd parked the way that he did... he was most likely already POed about something else. Getting shot isn't on my list of things to do, yet is becoming more and more common as people lose courtesy. As I told the officer last night; "My mother always said that it takes two to make a fight."