I have an e-bike I regularly ride for exercise around where I live.
Broadly speaking, there are a couple completely different product types both marketing themselves as “e-bikes.” The type I use, which I personally consider a “real” e-bike, is exclusively “pedal assistance.” There is no throttle and it cannot move on its own power. It simply enhances your own leg power by moving more than you would purely on your own power. This is mostly useful in causing less exertion for the same distance or elevation while still handling exactly like a regular bike in terms of gears, braking, balance, etc. These bikes also top-out the speed at which they will provide any assistance in the low-to-mid 20 MPHs, though it would take a ton of your own leg power to get to that speed or maintain it, except down hills. Overall I still get a decent workout but am able to do more miles than I would have (and perviously did) made otherwise and I can handle steeper hills that would have wiped me out without it. I usually use the lowest setting which adds about 20% to my own leg power.
Then there is entirely different product cynically marketing itself with the same “e-bike” label but which is really just a new generation of electric “mopeds.” These have throttles and can self-power using only the motor and don’t require human pedaling. And they can be easily modified by users to go far faster than any bike. These for the most part give real e-bikes a bad name. While these are really scooters that should be used on vehicle roads, users abuse bike lanes with them. In NYC many bike lanes are dominated by food delivery people on these, easily going 35-45 MPH, rarely stopping for pedestrians or red lights. Because they can go far faster than a real bike and because they don’t require self-pedaling, they can be dangerous to handle for some inexperienced riders who lose control, and because their speed makes any accident a more serious one. And these are what is causing many communities to restrict or ban e-bikes. I think the makers of these fake e-bikes knew they had mopeds with electric motors but saw an opportunity to re-brand and take advantage of bike lanes. The pedals are mostly for show – I rarely see people pedaling with them.