Indeed. If I plugged in every appliance I own and turned them all on at once alongside oven, shower, car chargepoint etc my fuse would blow. It doesn't because I don't...and that's what all electricity supply calcs rely on everywhere - it's called diversity.What else do you have running on electric in your house, the heating?
I have a 100amp fuse and two 32amp charge points that both charge at the same time.
That's only 64amps so there's still 36amps left for the rest of the house.
The Zappi monitors the overall load of the house and will reduce the current going to the cars to keep within the limit of the fuse.
You could have installed a zappi and not upgraded to a 3 phase supply.
Where diversity can't be applied - for fixed loads like car charging - then a different approach is taken. I could install two, three or four charge points and that would be allowed as long as they load balance. To say you can only ever have 32A allocated to car charging is nonsense.