You're the one making up rules. The fact is labelling a socket isn't a requirement, testing it's safe to work on is. It's not like you can't buy a really easy to use socket tester, literally just plug it in and it will tell you straight away, multimeters aren't even expensive.What a stupid comparison, labelling a random socket is 10 seconds work and a sensible, practical safety step. Labelling walls for buried cables is neither practical nor sensible…..
I best go label the sockets under my stairs, they're on the garage circuit.
Loft sockets are on the upstairs lighting circuit. Two of the garage sockets are on the kitchen circuit.