Riding a pedal-assist e-bike isn’t passive in any way. Just like with a regular bike, the more effort you put into pedaling, the faster you’ll go. Remember that you can adjust the level of assistance. In my experience, pedaling a 60 lb. e-bike (not including gear) at its lowest assist setting (usually “Eco”) on flat terrain takes more effort than pedaling a conventional bike at the same speed. If I’m feeling the need for more exercise, I go with a lower assist level. I only use the higher settings for hills.
I have a short 6.5 mile commute, but I live at the top of a massive hill with a 20% grade for nearly a mile. There’s no realistic way I could ever get up it without an e-bike, nor would I want to make that kind of extreme effort at the end of a long day at work. As it stands now, I can get up the hill at a max. of 10.5 mph with a good amount of sustained effort in the highest assist level and in a low gear. I can either reduce the assist level or increase the gear to improve my speed and level of exertion. In fact, I’ve gone from 8.5 mph to 10.5 mph in 6 months.