But really, there isn't much they can do.
The footage here was shot in front of the expensive London department store Harrods. It shows two things: the first is just how common it is to see supercars which have been brought in from overseas, as there is an almost endless procession of foreign plates. The other thing is how the cars' owners will often park them wherever they please. Tickets don’t bother them, as the tickets are seen as just being the price for good parking, and the money is insignificant.
One could simply say that, so long as they’re willing to pay the fines, then it’s their problem. But one could also see how this sort of thing could get annoying for someone trying to go about living and working in an already congested city.