My understanding is that is why they are limiting to 800w (~4A) at least in the UK's BS 7671 Amendment, which they consider well within the designed safety margins.
Ah yes, the good old "let's eat into the safety margins". This is why our motorways no longer have hard shoulders. OK, so cars break down less now. What justification is there for eating into electrical margins? The wiring in people's houses isn't getting any younger. And we still use the ridiculous ring system even in new builds in 2026.
Hopefully nobody thinks "I'll save even more if I get two!" and plugs them both into the same circuit.
Perhaps they could somehow detect each other and shut off.