What I used to see a lot of (especially on a Saturday) was a queue of cars waiting to get into the car park caused by 1 person who saw someone walking to their own car on the ground floor. They'd wait for this person to leave then slowly try to reverse into the spot (assuming the car behind them...
You should try working in a car park PPF! Parking across 2 bays is nothing, I once saw someone manage to park across 3 bays and then wonder why I was asking them to re-park their car.
Oh and as for this reversing in 1st nonsense, nothing is more guaranteed to cause a fight on a busy Saturday...