I worked for Standard Oil in the early 70's. They sent me to their company school to become an "automotive specialist". Ha. They taught me how to do brake jobs, tune ups using their diagnostic machines, headlite adjustments, undercoating of vehicles,etc. Then they sent me to a station that didn't have any of the equipment to do that type of work. So, I pumped gas. To answer your question, the stations had to be "certified" to do some of the work like smog certificates, brake certification. In addition to the stations being certified, the mechanics had to be certified too. We all had to take test and receive so many hours of training in order to do this type of work.
Now, anyone can do a brake job, but if you needed a "certification" on your vehicle in order to get current registration from DMV, then you had to go to a state certified station.
That's my story, and I'm sticking too it.
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Don "oltoydoc" Sherwood
Vintage Gas