Also, houses don't pull 200A all the time. The duty cycle is pretty low for the majority of people. Where I live, there is one transformer for each 3-5 people. They are not sized to handle all houses at full load for any length of time. I don't recall what the scaling factor is around where I live, though.
I don't know what is typical but I have one of those whole house energy monitors and my average consumption hovers around 270-300W when I'm home during the day and 400-600W when I'm awake in the evening. During the rare power outage that occurs I run my whole house pretty comfortably on a little 2kW inverter generator. I can't run the microwave, clothes dryer, air conditioner, the air compressor in my garage or other big loads but that big stuff is used only occasionally anyway. The peak I've seen in my own house was around 18kW which was a time when I was using the hot tub which I only keep filled part of the year, and had a load of clothes in the dryer and some other stuff going on. I have gas for heating, hot water and cooking, the latter was originally electric so my 200A service is probably larger than really needed today. For some reason most US home have electric stoves for cooking, even those that have gas to the house for heating and hot water. I prefer a gas stove and have never understood why they are not more popular here but I know some people fear the possibility of gas leaks, mostly older people who remember the days of standing pilots with no thermostatic control on the gas.