An air carrier Captain reported that manned ground equipment encroached on the gate safety area and were reluctant to move even after a seven minute delay.

Narrative

EQUIPMENT CONTAMINATING THE GATE AREA Several pieces of ground equipment were encroaching into the gate freedom area. One cargo loader had an operator on board and saw that we were not taxiing in because of his being over the line. However; he ignored this and continued to wait for something to happen. Another ramp person waved a signal of disgust at us; presumably because we refused to continue into the gate with equipment over the line contrary to SOP and common sense. We experienced about a 7 minute delay which was totally avoidable. It was apparent that the ramp personnel had no concern for this safety hazard or any respect for my crew performing according to SOP. This is a very common problem at the SFO International terminal. I have written this up several times. This continuing problem has been brought to the attention of the flight office; the station manager; and VP of Safety. Yet; the problem continues. The station does not seem to be able to adequately train the ramp personnel. The ramp tower controller should bear some responsibility as well; as he looks right down at gate.