You people make it sound like your average parking lot is the autobahn
90% of the time, there are no cars or pedestrians in the area where you would be backing out of your stall. That makes hitting something much more likely if you're backing into a stall with cars on either side than if you're backing out into a space with no oncoming vehicles or traffic.
Of course, most of the time you can back in without affecting anyone either. But if there's a car behind you that has to wait for you to back in (and lets not pretend you nail it on the first try every time) then be polite and either go pick another spot, or pull in forward.