Yes, I agree with that. Restricting sale would probably prevent DIY work, but wouldn't really be politically acceptable in the current neo-liberal mindset. Though I have a hope that things may start to turn around again and I'll keep my fingers crossed that the socialists won't make a mess of it a second time
"Don't think it was as he's posted on the sparky forum[...]". Are you referring to my (badly explained) Grenfell comment or to someone else's comment?
My point about electrics is that the person replacing the cable would not be able to test the cable to the IEC standards through lack of proper equipment, so could not possibly meet the requirements. But then, replacement of a section of cable is not (usually) notifiable work (which would require at least the circuit testing to be done professionally or by building control depending, I think, whether you are in England or Wales).
In practice, I suspect not many cables are tested in this sort of situation, and, when an electrician can report a bad earth to the DNO and then DNO guy comes around, pretends the earth is okay and then gets annoyed, saying, 'it doesn't matter anyway because the RCD works!' (true story, not sure how the non-RCD protected circuits in that house are, then, even reasonably safe!), what hope have we?
To come back to our own industry, I'm equally bad. I don't have a pressure testing kit (don't personally know any plumber that does), so you could argue that none of my plumbing work actually meets the Water Regulations because it has not been pressure tested in accordance with the relevant procedures.