Actually, it is possible to get US EVSEs that can charge at up to about 14 KW on single phase power, my friend has one on a 60 AMP circuit for future proofing.That won't make difference with domestic charging unless you have a 3-phase supply. On single phase you still get 7.4 kW at 32 amps. It's purely for certain countries that limit domestic circuits to 16 amps each but have 3-ph.