I wanted to use them when I was a student and lived 2 miles from campus. Unfortunately I couldn’t ride on campus, and I couldn’t ride in the residential area where I lived. So basically I could only ride in between - one mile out of the two. I just got a bicycle which didn’t have such restrictions.
Right. The popularity of e-bikes is partially just regulatory. An e-bike can go 2-3 times faster than a Bird scooter, but it looks like a bicycle so it is legal to ride more places.
As far as I know you can't really ride your bike on the sidewalk. Either the street or specialised bike lanes. So you will never really see someone driving a bike at 25 km/h (the legal limit in many European countries) on the sidewalk.
Plus, people are much more used to dealing with bikes than scooters.