Tags are good to catch the accidental things that happen, not the intentional. Of maybe 50 occasions where tags were caught for intentional misdeeds, zero of them weren't one of the following:
1. the plate was stolen,
2. the vehicle was stolen,
3. the tags were not real,
4. (most commonly) the tags belong to the vehicle, but the owner of the vehicle doesn't have control of who is using the vehicle. Typically 'drug cars' that tweakers share or rent to each other for money even though it isn't theirs. Cops give up on these because it always leads to the same people they are always dealing with and nobody wants to foot the bill to keep them locked up. Everyone has plausible deniability because they can prove they were someplace else at the time. Half the time, its an innocent grandparent's vehicle where they are trying to help out someone.