I just figure that those that are considerate of others change lanes and are prepared for the road narrowing accordingly. Its the rude people that wait til the last minute and then force their way in. I would venture these types cut into lines elsewhere as well. Doesn't bother me though since I am already in the appropriate lane.
You can't define it, and neither can I. The final arbiter of the merge is the end block. I'd just as soon every car would aim for the end block and every other car in the flow lane would leave a space for merging at that point. It's not gonna happen, so I prefer to drive in the reality and not the fantasy. Then nobody has to "force" their way in.
BTW, that same mindset happens on perfectly legal on-ramp merges. Folks don't want to allow other folks into the flow of traffic ahead of them. Be honest. When we close ranks, it's really about not letting someone get the better of us. To the detriment of everyone behind us.
I think it's far better to extend grace to the undeserving than to try and triumph over petty tresspassers.