The difference is effort. Just dropping it over the ground is the least effort to accomplish getting it out of the way to move by. And not going out of your way to put it someplace else. You aren't committing a crime in the process by stealing anything. And they're likely to not check and just leave it there anyway for a punishment later when they notice it missing.

Taking the pin out means it's no longer secure, it could fall out on the highway, damaging an innocent vehicle following at a later date.