Auto change to departure is not a good idea because of the separation issue. Tower might need to keep to departure for a while to separate it from other traffic visually.
I would guess the helicopter traffic to/from GFS.
Why is the separation issue not a problem at the zillions of places that do autoswitch to departure?
Maybe because other airports are not squeezed right up against a line of hills up to about 3000'. Helicopter traffic needs to approach and depart the field in close parallel to the fixed wing tracks