What legislation is that? Schuko portable EV chargers run at 12 amps, 75% of the 16 amp rating. That's what VW ship with their European cars...
You are right, I stand corrected, it isn't mandatory legislation, just national recommendations. Actually here people and companies take those recommendations seriously enough that finding a schuko portable evse over 8A takes
some effort, only better equipped stores sell them. (And you can hear claims they are illegal when they are not. In any case, the whole discussion triggered from poor safety of 16A rated Schuko sockets and plugs when used anywhere near 16A, across many well-known manufacturers, even when the plugs are not visibly damaged. As mansaxel points out, 10A would be a more suitable rating.)
A decade back, I was present when there was lobbying going to make that 8A limit into EU legislation but I'm glad it didn't happen. But car manufacturers seem to take that seriously, too, e.g. Nissan Schuko chargers run at recommended 8A.