Yeah, I think it's selfish. And weird.
Yes, there may only be a handful of people with nothing better to do than do it twice, so it might not make the wait any longer for others.....but they don't know / care about that, do they? They'd still be doing it regardless of how many others were also doing it and how long it may be delaying things for others.
You do come across these types of people every so often. They seem to just exist in their own world and have no regard for other people.
I came across one just the other day. Was waiting on train platform. Chap sauntering down the stairs, right in the middle, casually, slowly. Train was pulling up. Another chap came jogging down the stairs behind him to catch the train and was heading to the left to dodge around him. Sauntering chap happened to drift to the left and blocked him. Guy tried to go round the other side and the guy casually blocked him again. Rushed guy said excuse me. Sauntering guy just had a complete lack of urgency and refused to either hurry up or let the guy passed.
Rushing guy missed the train.
Couple of people looking at the sauntering guy like "you git".
Sauntering guy completely oblivious.