Service stations mean lots of things now. Many in my area mainly pump gas (most are really pump it yourself) and maybe change or repair tires and a few minor things like wipers and light bulbs and oil changes. I think a lot of their money comes from the safety inspections. That is about all that is required of by cars of today. Anything else is usually a major repair and requires lots of skill.
I remember years ago that oil was changed every couple of thousand miles, spark plugs and points around 10,000 and a few other things that did not require a lot of skill to do . Now oil is good for 7000 or more, plugs to 100,000 and no points. Most of those jobs could be done by many of the teen agers that I knew back around 1970.
Auto techs are mainly in shops of their own and do not fool with gas or else they work for one of the large motor companies.