A large (probably over-size for most users) EV battery is 360MJ.
It seems reasonable we should be able to fill the EV battery overnight, let's say 10 hours between we plug the EV in to charge (empty) and expect to find it full.
So that 36000 seconds, and conveniently that gives us 10kW power input. Which sure enough is about 40A.
So, not "a lot more" electrons. Transitioning other energy uses to electricity will increase the load at individual homes and to the grid but it isn't an order of magnitude thing.
A mistake commonly made here is that people look at energy equivalence charts and they assume that 10GJ of gasoline means we'd need 10GJ of electricity to do the same job. But in fact ICE is hideously inefficient, we used it because it was convenient and for no other reason, so electric cars have always been several times more efficient than 1:1 on that basis - that just wasn't good enough reason to switch before.
I have a 200 amp panel. Today that's fine, but my home is heated by gas, my food is heated by gas, my pool is heated by gas, and my transportation is powered by gasoline.
Let's be naive and say that the panel was properly provisioned for the loads in the house when it was built in 1975. Now let's switch out gas heating for a heat pump, costing us 40 A. Induction cooktop? 50 A. Oven? 50 A. Two EVs? 100 A. Pool heater? 50 A.
Having a 400 amp panel quickly starts to sound pretty good. On the other hand, so does having a huge solar array and a bunch of batteries. But code and permitting and PG&E does not smile on such beefy residential installations.
