On most modern EVs, that's at least 3 days worth of power if the vehicle is not being driven. Larger vehicles naturally have far larger batteries.

Mmmh no? 90kWh battery packs are not that common. An M3 or MY LR AWD have an 82kWh. Some Mercedes and some Chinese model have a 100+kWh battery but the most common setup is between 60 and 70.

Anyway I agree that in emergency conditions it can go a looong way for a house.