Vehicles Parked on Road with no tax, no Mot etc.

For several months, multiple vehicles are parked for weeks on end without moving, that when checked have no tax and often no MOT. Some are being moved from time to time and sold by a local resident. If no tax is paid, these vehicles should not be parked on the public highway and must not be insured. Despite reports to DVLA no action has been taken. There are currently at least four vehicles (often identified by white writing on and blue circle stickers on the windscreen and barcodes on wing mirror glass). Looks like these are potentially written off cars that have been purchased at auction.