What mental disorder does this fall into?
This is totally bouncing off of me. How can a person, in a public space, surrounded at all times by other people, just forget they exist for any amount of time, for any reason? They're fucking everywhere. They're breathing, they're talking, their cart wheels are squeaking, the footsteps from their rubber-soled shoes are echoing off the hard tile floors, how do your senses just stop registering any of that?
Yes, I am incredibly unfriendly when I'm trying to get my shit done. I want to be out of that place as fast as fucking possible. I don't want to linger, I don't want to chat, and I sure as fuck have never in my life been so distracted that a hundred other moving, talking people just vanished completely from my awareness. Is that some kind of ADHD thing? Some manifestation of executive dysfunction, like always being late and never letting anyone else talk in a conversation if they can't actively shout over you?