You sound like a moron.
Ever driven a big SUV or truck? They are a pain in the ass to back out in, especially in a tight and/or busy parking lot. If you are pulling in with no traffic around, it's easier to back in instead of trying to back out with a lot of traffic.
Ever see how some people, when about to make a right turn, swing out to the left? It's because they aren't very good drivers and have trouble making a tight right turn. Swinging out gives them a better angle. In a parking lot, with oncoming traffic, you can't swing to the left to get a better angle, so some people find it much easier to reverse in.
Ever workout (of course you haven't). Some people, anticipating being exhausted after a hard workout, don't want to deal with trying to back out and not being able to see people/other cars if it's at night and/or if they have two big SUVs/trucks on each side of them. As a result of knowing they are going to be tired and just want to easily pull out, they reverse in.
Ever parked on a busy street usually in a shopping area? Those spots allow perpendicular parking. Instead of having to right the high amount of traffic and impede traffic, they want to be able to quickly pull out.
Ever parked in a spot and know that when you leave, you will have to reverse out across both lanes to go in the direction you want to travel? Instead of having to wait minutes for that, it's easier to reverse in.
Ever parked in a city parking garage where it is packed and the spaces are very narrow? It's far easier, especially with a reverse camera, to reverse in then it is to pull in normally.