Why wouldn’t fast home charging scale? Presumably, homeowners are doing their own installations.
Because current grids are not setup for 10,000-watt chargers in every home and/or parking spot. Just think of trying to provide chargers in an apartment complex, one to each apartment. The power requirements become crazy very quickly. This parallels the issues with rental car companies trying to charge dozens of cars at once, such as at airports. Our grid standards never conceived of such loads becoming commonplace. Whereas today when every EV owner just expects their home charger to be available 24/7, if everyone had an EV some sort of rationing/scheduling would be necessary
Some parts of Canada have already seen this with heat pumps. People were encouraged to switch from natural gas to electric heat pumps. But incentives have been withdrawn as power spikes during cold weather challenge local grids, especially when there is no wind/solar power available locally (think cold winter mornings in the midwest/prairies.)
600W is not much, that is an average gaming computer running a somewhat demanding game. Nerds all over the world have this as a multi hour nightly ritual. I choose to charge my car now and then instead :P
It exists now as an incentive to buy EVs, but as EV become more popular it's bound to disappear.