One possible reason against backing into a spot:
In a crowded parking lot – say, around dusk – might it be easier and safer for other drivers going down the aisles to be able to see the REVERSE and BRAKE lights on a car backing out of a spot?
A car that backed into the spot may nose out without much notice or fanfare. Brake lights and reverse lights especially always grab my attention.
Headlights tend to be much brighter than reverse and brake lights.
Only if you have them turned on!
And how would I know that you’re not planning on turning into a parking space ahead of you, as soon as a car/person I can’t see gets out of your way?
If the car’s rear end is as close to the left side as possible, the left turn signal is on, and the car’s front end swings to the right, that’s a pretty unambiguous sign that the car is preparing to back into a space on the left side.
Don’t follow too closely, and observe what the car is doing.
And the difference between a car that’s stopped, with no turn signal on, at the left side of the aisle so it can reverse into a space and a car that’s stopped, with no turn signal on, at the left side of the aisle so it can pull forward into a space is…?
If the car’s turn signals are not on, you should generally assume that it the car is not about to turn.
Even if you assume the driver is breaking the law, it shouldn’t be very difficult to see what the driver is intending to do. If the car stops at the left side of the aisle, the car is either preparing to back into a space on the left, or move forward into a space on the right. You should be prepared for both possibilities and keep a safe distance.
Another reason for backing in is if you are having battery/starting trouble. A lot easier to hook up jumper ccables if the hood is facing out. That’s really what got me started.
Yes, this.
As a dedicated backer-inner, though, I’m aware that a driver right behind me might not understand what I’m about to do, even if I use turn signals. So if someone is right on my butt in a parking lot I don’t back in; I drive up to the next empty spot.
Your just fuckin" lazy if you don’t back in when given the oppertunity.
Well, duh. One is a car that’s stopped, with no turn signal on, at the left side of the aisle so it can reverse into a space, and the other is a car that’s stopped, with no turn signal on, at the left side of the aisle so it can pull forward into a space.
Thank you. I thought that might be the case, but I just wanted to check. 
As someone whose garage is far too narrow for me to safely back into, I’d like to mention how much I enjoyed it just now when I got a load of the OP’s username.
That is all.
If it’s too narrow to safely back into, surely it’s much too narrow to safely back out of??
SCAdian, just think of parallel parking on the street, and how you must not follow so closely as to prevent the car in front of you from driving past the open space and backing into it. The same applies to parking spaces in parking lots.
Since the odds that a person in a parking lot is parking are close to fifty/fifty, you should drive accordingly, rather than follow too closely.
If the person wishing to park fails to signal, there is a problem. If the person following follows too closely, there is a problem. Two wrongs don’t make a right.
When I was in high school we did it because, it looks cool!
I’ve matured a little since then.