> I'm not saying it doesn't. I'm saying, even considering it, nothing jumps out to me as a reason it should be obvious.

I'll ignore questions about the distribution and highlight what is perhaps the most egregious problem in EV estimates:

Energy is the wrong metric.

Using the average allows one to speak in terms of energy. Yet energy isn't what we need. We need power. Yes, of course, at the end of the day you are trying to store energy. However, what we need to know is what our power requirements might be.

Here's a super-simple example. This isn't meant to be a full analytical model, it's just a simplified hypothetical used to illustrate the important difference between speaking in terms of energy and power.

Ten EV's are driven the same number of average miles in a day. The number of miles does not matter.

If those ten EV's are plugged-in for slow-charging all night, they receive a certain amount of energy. This energy is delivered slowly (at a low power level) over, say, twelve hours.

On the other hand, if the same ten EV's where to simultaneously plug-in for rapid-charging in, say, one hour, the situation is much different. They would receive the same energy. However, this requires twelve times more power.

The difference isn't trivial. It's the same energy, yet you need twelve times more power (and the ability to deliver that power) in the second case.

Real-life hypothetical:

Hurricane landing in Florida at some point in the future when EVs (from motorcycles to semi-trucks) have fully displaced internal combustion vehicles.

A very large percentage of the population needs to rapid charge during a very narrow window of time. Everyone is on the road evacuating. The limiting factor is power generation capacity as well as power deliver capabilities (the "grid").

This is a highly simplified view into why using averages to broad-stroke estimates is in the realm of a fantasy. You don't have to look at natural disasters as the only drivers for this sort of peak demand. Holiday traffic and other events or local conditions alter the distribution.

Regional differences have the same kind of influence. For example, where I live, most people have to drive 30 to 60 miles each way to go to work. That's hundreds of thousands of vehicles. Bad urban planning? No argument from me. Guess what? It isn't going to change. Anyone who thinks so has never had to pleasure of locking horns with the urban planning agencies where they live. Not going to happen. And it isn't just work. Entertainment, high-end restaurants, etc., are also 30 to 60 miles away.

That's why using averages to calculate energy is only valid if we are OK with people not being able to charge their cars and being stranded when peak power demand exceed available generation and grid (transport) capacity. In CA we've had cases of people not being able to charge their EV's during evacuations and being asked to delay charging during periods of high heat.

I have written simulation models to analyze this at a reasonably detailed level of granularity. My model predicted the need for additional (new, on top of what we currently have) power generation in the order of 900 GW to 1400 GW for the entire ground transportation fleet in the US going electric. I did this many years ago. I have since concluded that this range seems to be an accurate prediction. For a sense of proportion, this means we need to build a thousand nuclear power plants. No, solar and wind, individually or collectively, won't do it. I've done the math on that too.