I have been at a few airports recently and I have noticed that at each gate there is a line in which the aircraft must get in line with. The one thing that got my eye is that there are different points at which different aircraft must stop their front wheels at and what even got me more was that at the same gate there was different parking points for a B772 and B773. There was only a few feet in the overall distance of these points.
The question is why dont they have the one point for all aircraft? what happens if an aircraft parks on the wrong spot? what happens if the marshall directs the aircraft to the wrong spot, does he get in trouble?
It could have something to do with jetways that are connected to the airport building, but they are manually operated.