Many years ago, when tax discs were a thing, I got chatting to a real life policeman. He had a whistle and all. There had just been some puff piece on teh news about police resenting acting as tax collectors and how they shouldn't be checking VED. (I can only presume a senior minister was caught in flagrante sans tax)
Anyway he - very carefully - commented that generally stopping a car for no tax "usually" revealed "other offences" that made it a valuable tool in the war against criminals.
(I paraphrase, he spoke "copper" and I can't reproduce the words here).
It seems to be a law of nature that where you find one illegal act, there will be a string of others.
A couple of years ago, there was a dramatic stop on the M6 by Aston. Car full of wannabe gangsters was stopped with a bootfull of guns, shotguns, pistols and machine guns. Cue much defence action about profiling and the legality of the stop. Quickly withdrawn when the police pointed out the car had not MOT, tax or insurance.
Please, never ever ever credit criminals with any degree of intelligence. They really aren't. I mean really really aren't. Just look at the mensa rejects being locked up by the dozen right now. How many of them would you trust to sit the right way round on a toilet ?