Supply line voltage is irrelevant. The car and charger negotiate power and voltage dynamically.

Charging stations typically also have on-site battery storage to have peak charging power that exceeds grid supply (and also because energy arbitrage is profitable).

Local codes might limit things, but that is unlikely.

Local codes for residential? I doubt anyone would be doing flash-charging at home. If you're referring to codes for charging networks, that would fall under industrial fixtures; and industrial codes allow for scarily-high-amperage wiring under a stricter regime than residential.

Industrial codes often only allow trained electricians to connect those high voltage wires. Even though it is fine, it is against the code to plug in that cable.

Flash charging delivers over a megawatt of power via a thick actively-cooled cable. This is for rapid charging stations along highways (equivalent of gas stations), not for a DIY install in your garage.

This is about needing a licensed electrician to connect that cable to your car when you are a that rapid charging station on the highway.

The letter of the law often says things like that.

[delayed]

I am very well aware that the connector is foolproof. Hope the law was written years ago when nobody but trained electricians would even dream of touching anything more higher voltage than a US, than a standard household. All it takes is a few people who have an irrational hate of EVs, which we know a lot of those exist, and they will just apply the law and some of you can't charge your EV in a certain area at more than level 2.

The above has nothing to do about safety or how practical it is. It is about people who can apply the law to their twisted ends.

Currently the fastest chargers use 1000 V.

There are international standards for 1000 V and 800 V charging, but I have no idea whether they are allowed in NA.