If the DVLA really enforced illegal spacing they wouldn’t have a business, what they do at the moment is just scratching the surface, there doesn’t seem to be any motivation to really deal with it, I’ve seen numerous plod driving straight past a car with an absolute piss take of a plate, I don’t think they can be bothered with the paperwork.
Look at the mount of complete tat that goes through their auction, the only value in the plate is to butcher it, and the DVLA are complicit in that.
The real solution is for the DVLA themselves to press them all in aluminium, ban third party manufacturers and set a date that they all have to be replaced. It’ll never happen so Shinyplates show plates will keep peddling this illegal crap whilst the demand exists.