If you want to do something about this, given that we have universal surveillance of license plates anyway:
Demand that your local government installs PM 2.5 / 10 monitors on each of their spy cams. They'll easily pick up out-of-spec emissions systems. Join the emissions spikes with the license plates. Take the cars that are two standard deviations above the norm for PM 2.5 / 10 increases after they're spotted by the camera, and have them come in for an aggressive smog check.
Completely eliminate all other smog check requirements for late model cars because modern tests are just "check the pollution control light on the dash", and "check for tampering". Those checks will only catch honest drivers, since coal-rollers limit themselves to reversible modifications anyway.
If we're going to give up our privacy for some amorphous benefits (which I think is a terrible tradeoff), at least let those benefits include annual paperwork. As a bonus, if the PM 2.5 / 10 data is made public, then we'd have much better air pollution monitoring. There's no way this plan costs more than the current system, where every ICE car driver pays ~ $100 to an inspection station every few years. PM sensors are under $100, and you need orders of magnitude fewer sensors than cars.