Why does the load across wires need to be balanced; why can't the heat or other side effect not be tolerated? How much inconsistency are we talking about on these unbalanced German wires?
If a three-phase load is not balanced, so that current flows through the neutral wire, you get less power out of it. To take an extreme example, connect a Type 1 plug between L1 and N, leaving L2 and L3 unconnected... unbalanced, only 1/3 the possible maximum power. The clever thing about 3-phase is that it is a way of getting any combination of loads up to 3 x what you could do with 2 wires, but using only 4 wires of the same thickness carrying the same maximum current. In both cases, plus a protective earth when appropriate.
Furthermore, as you have argued convincingly that it is so much simpler to convert 3 phase AC to single phase DC, why did the EU re-engineer EVs to each contain a complex mix of multiple AC chargers instead of simply adopting a pre-existing (and foreign) DC charging standard like CHAdeMO? Does the EU suffer from a "not invented here" mentality?
This isn't a German plot, and when the EU was agreeing the standard, that negotiation included significant input from the UK (we used to be an important part of the EU, for a brief 40-ish years, until we left that club). Having taken our nice new(ish) EV to France and Ireland last year, I'm very glad the charging connectors are compatible.
And we don't specify just a DC charging standard because it would make home and destination-type fast
charging installations prohibitively expensive. The point of providing AC charging is to make charge points feasible anywhere there is mains power: industrial estates or farms with lots of 3-phase, more than half of homes with 1-phase, lots of homes but especially Spain, France and Germany with low-current 3-phase. All can have charge points with the same socket and these then work with practically any plug-in car on the roads. A CHAdeMO home charger would cost a fair bit more than a mere EVSE charge point.
Multiple small chargers is more energy efficient than a single high-power charger. (Each AC-DC converter has a more or less constant rate of power wasted as heat. It runs at its best efficiency when fully loaded. By switching in only as many converters as needed, the wasted power is less than running one high-power converter at a fraction of its maximum.)
It's time I stopped letting other posters here wind me up. I'll try not to take the bait next time.