I was managing a ‘service station’ in the late seventies/early eighties, the ones that did mechanical work on cars and dispensed gas. Gross profit on a gallon of self serve was 8–10 cents; gross profit on full serve was 25–30 cents per gallon. Net profit for the month came from the service work.
It was the era when ‘C’ stores (convenience) started being built by the major oil companies, They were larger, more pumps, more customer friendly, and provided greater volume of gas sales and better profits on groceries. That began the domination by the self-serve-only ‘gas’ stations. Then came Jiffy Lube, etal., which stole more business from the traditional service station model. Full serve is still legal in my state, but the stations that offer it are few and far between. With rare exceptions, there’s more money in self-serve gas and groceries than there is in full/self-serve gas and auto service work.
It’s the free market at work.
As for safety, we’d have a hose pulled out of the pump once in a while, but the safety shut-off valves always worked. The scariest events were when somebody pulled up to the pumps with flames coming from under the hood, thinking that they could use the water hose to put out the fire!