So, apparently there is no mandatory vehicle inspection in the US. Of course there isn't, it would violate the freedom to drive with an unroadworthy car.
The state of Washington is an interesting case. They had annual inspections and then somebody ran the numbers and found that so few cars were being flagged, that it was an enormous waste of resources. They got rid of their inspection requirement. More programs should be run like that. Set a goal, create a program, then periodically evaluate if the goal is still the same and if the program is effective.
The state strongly encouraged me to send it to a Golden Shield mechanic. As part of the work, they "checked" the air intake filter and MAF sensor on the engine, which was, of course, filthy. It sits in a big plastic box on that car. Instead of reinstalling the filter, they jammed it in sideways and closed the box. I figured it out later, and spent about an hour picking bits of leaves out of the downstream air intake.
Of course, this cost 95% of the limit past which California gives you a free pass till the next smog inspection. (And almost 2x the market value of the car.)
I'm convinced the whole thing is a make-work program that's holding our air quality hostage. (And I'm strongly for tightening emissions standards!)