That's assuming it makes the least bit sense to compare the distances people typically walk when that's the available mode of travel compared to how far they ri

That's assuming it makes the least bit sense to compare the distances people typically walk when that's the available mode of travel compared to how far they ride when they have e-bikes. And "sustainable" isn't even primarily about energy efficiency - it's about ensuring we don't exceed the capacity of the planet to repair what damage we do it. A human population that relies primarily on walking (or push-biking) to get around is almost certainly going to be far more sustainable than one primarily using e-bikes.