+1 mountainclmbr about how driving in LA works.
fistful, you are right in principle, but in practice driving like that in LA will get you killed. There are way too many drivers that think the speed limit is just a suggestion. In fact, that seems to be the rule, not the exception. It is far safer to move at the speed of the pack. Highway patrol and police have ignored "pack speeding" on ALL occasions I have observed. The guy that gets a ticket is the loner that does 95 on an empty road.
Nicety has nothing to do with letting people merge or change lanes in front of you. It is common sense to do so. It is the safer way to go, especially when it is obvious the merger has very little visibility and a short ramp. I'd rather make it from A to B in one piece than worry about if I have the right of way over the merger. By the way, insisting on your right of way is illegal in California, because it is unsafe. However, in practice you sometimes cannot change lanes in heavy traffic without making it abundantly clear that unless they back down, you will hit them. Go figure. It is a crazy world.
Yet, the thing that really pushes my button is when they speed up to prevent you from merging/entering their lane because they saw you signalling. That's just plain dumb reckless.