There's an interesting subculture of license refuseniks in the UK.

It does indeed seem to be true that the detector vans are pure PR, with no useful electronics. According to legend no data from a van has ever been used in a prosecution.

But it's a sad business. A lot of people who are caught and fined incriminate themselves unnecessarily.

They're almost always at the poor and not very educated end of the population, and will always accept a rubber-stamped prosecution because they literally have no idea they can often put up a defence in court.

Really, fining them four figures for what is really a trivial offence is unhelpfully nasty and persecutory.