Seems like it should be as simple as converting AC to DC., passing on all available voltage (up to a safe limit) to the car, and stopping it when the batteries are full.
Similar to what a wall brick does for your devices on a smaller scale, though the brains are in the device not the wall brick. Why isn’t that done with cars?
I see mention of ‘different technologies’, and ‘better chargers vs lesser chargers’, etc. and I feel like there must be more to it.