I'm cool with it if someone is clumsy, for whatever reason, or dizzy, has dyspraxia, is trying to handle a kid with a tantrum, etc. You're fine. But for some it seems to be totally on purpose. Like... I won't move. You move. Subconsciously seeing others as not mattering.
I'm happy to move aside if it seems necessary, or just so we don't all bump into each other 24/7. But some people (and this ain't no complex) just expect you to be the one who moves, and it gets old. Like people can sense who's the anxious one, the one more likely to move. I'm short and quiet and sometimes have felt like I'm seen as an easy push or an empty space... maybe not even on purpose, just, subconsciously.
I've even noticed myself do it very occasionally. I only do it when I've had it up to here moving aside, either on the street or putting my needs second, and then I stride along like I'm ready to murder something, and you'd be surprised who moves. Like we really do have law of the jungle or something. In this case there's a chance I have been the one described here as the selfish walker - but only when I have zero f---s left to give. And even then, I don't do that just to stand in the spot someone else had, or to barge into someone's path when there was tons of room, that sort of nonsense.
Lastly, a shout out to teenagers (in my area anyways), they are polite and will let people through! Even the 'toughies'. They rock. If you say excuse me, they will. And I move some for them too.