I don't think it's that different. Even in suburbia kids and teens still use bikes as transport.
And are E bikes that popular in the east? Are they more popular than they are in the west? Outside of couriers that is, it's easy to justify why they would use them.
I don't view them as a form of exercise, I just think riding a bike isn't that hard and if you are using them to go from place to place you may as well get the most from it.