The UK system associates the plates with your car. This incurs basically two pieces of paperwork online when you sell it, one of which is also annual taxation.
The administration has gradually modernized so that all the legal requirements of tax/registration/insurance can be checked online.
However, there's a loophole that's apparently becoming popular: "ghost plates". Number plates aren't a secure document. They have no authenticity markers. So you can just.. print your own, slap them on, and you're very unlikely to get police attention. A subset of that is plates which are IR scattering so they don't show up on speed cameras.
"Loophole"? The secret ingredient is crime...
> However, there's a loophole that's apparently becoming popular: "ghost plates".
We don't call fake IDs either a loophole or "ghost IDs". When presented as identity documents, they're fraudulent identity documents. It doesn't matter if that ID is being presented to a bouncer in order to get in to a bar, or to everyone who cares to look at your car's bumper while it drives down the motorway, it's still a fake ID.
> A subset of that is plates which are IR scattering so they don't show up on speed cameras.
Only these are "ghost plates". So called because the letters appear faint, or ghost like, on ANPR cameras.
Using illegal plates, either ghost ones or cloned ones (where they're real plates but for the wrong vehicle) are not loopholes, any more than breaking into someone's house and stealing their stuff is a "loophole" for property ownership.