Because every car needs to charge 1-2 times per week and you also don't want to park 10 blocks away from home. Maybe 50% coverage is indeed excessive, but it is

Because every car needs to charge 1-2 times per week and you also don't want to park 10 blocks away from home. Maybe 50% coverage is indeed excessive, but it is correct ballpark estimate. Maybe you can get away with 20-30% in cities with less lazy (and more coordinated) people :)