Cincinnati, Oh. used to have safety inspections that were required annually. They were county specific and pretty much a way of making money. If I had an old beater that didn't stand a chance, I went thru the Norwood Safety Lane where 4 wheels and a motor "passed". Norwood was an incorporated city inside Cincinnati, so their sticker counted. When it started to cost the city more to run the inspections than they were making, it stopped.
And big trucks and trailers were never checked, because the safety lane building didn't have big enough doors.