To me, it seems objectively easier to pull into a parking space forward and then back out of the space when you are ready to leave. You don’t have to line up with the lines while driving backwards, and it’s easier to keep from hitting other cars as well. So why back in? To me, the only advantage I can think of is that you can get out quicker, technically.
Edit: I do not need driving instruction, just wondered why. The reasoning.
I have a private parking spot off street in a city. I don’t like backing up towards the main road; since it has pedestrians and stuff. It’s a little harder to see.
So I back into the spot. It’s way easier than backing out - and pulling out is even easier. 
My work parking garage is already really tight. It’s another situation where backing in is easier than backing out - and driving forward our is even easier. So just some planning.