I see a small version of this every day in a part of Austin where they have back in parking places. Person "A" stops and throws on the reverse lights, person "B" behind lays on the horn, road rage ensues.
Me, I don't even try for that parking, and park on a side street where there are plenty of quiet spots just 100-200 feet away.
I think the OP is encountering the same mentality that people get at strip malls... the herds fight over parking spaces right at the front, but if they don't mind walking a few feet, there are aisles of empty places far from the carts and other traffic ready to be used.