You are so right...
I think the problem is the perception you get when you look down the length of the truck. The main body curves from front to middle and then to the rear. Even tho' the fenders are equidistant from a wall or whatever, it appears you are not in straight.
It is also hard for me to know when to stop when backing in. Fortunately, I usually stop and then realize I can go back some more.
Diggs