they actually built systems for this but it has never been implemented. Basically you make the cargo hold completely removable from the plane. There is a box that slides in and out of the bottom of the plane. Someone just drives up with a fork lift style vehicle pops off the container and takes it inside the terminal where it can be dumped out onto the conveyor belt. I am surprised they have not automated the entire baggage system. It seems like it would be feasible to automate just about everything. You know where the plane is going to park every single time just fix that position and have something under it which can directly attach to the plane and pull the bags off and conveyor them under the ground and into the terminal and it can auto sort the bags to the right destination. It would not be easy to build but it is doable and would remove the need of large percentage of workers in the airport

Perhaps this would require bomb-bay doors on the bottom of the hold?