Pilot reported that ground vehicles drive directly in front of the aircraft at the gate prior to pushback even though the taxi light is on to signal impending movement. Reporter stated this has occurred at different airports and is a recurring issue; indicative of poor ramp staff training.

Narrative

I'm seeing a re-occurring issue with our Ground equipment not yielding when I begin taxi. This is especially prevalent in ZZZ and ZZZ1. In ZZZ; pushback is fairly shallow and straight back. In order to get the aircraft to turn; I have to get the aircraft to roll forward slightly prior to beginning the turn. This leads to the wingtip crossing over the painted ground equipment 'ROAD' on the ramp. Prior to beginning forward movement I turn the taxi light on a signal that the aircraft is moving. However; our own Ground traffic (including catering trucks) never yield and drive directly in front of the aircraft. I often have to stop the aircraft to allow the ground equipment to pass. This is unacceptable and a symptom of poor training of our Ramp Staff. We are asking for an incident where a scimitar winglet aircraft has contact with a catering truck; or worse; where we have an actual crash between ground equipment and an aircraft. In addition; once I've stopped the aircraft; after rolling forward; it makes the required thrust to complete the turn greater; leading to increased likelihood of injury or damage due to jetblast. Train our Ramp staff properly and reiterate the need to avoid driving in front of an aircraft with the taxi light on.