People have been using “ebikes” on Seattle’s multi-use trails for some time. These are primarily pedal assist ones capped at 15, 20 or 25 mph. Our household recently got an electric cargo bike with this feature. It’s great because it’s insurance that you can get where you need to go, even if a little tired or the hills are bigger than you realized on the route you picked (a critical need in a city where we have not yet put protected bike lanes on major flat and direct arterial routes).
Technically, ebikes on trails only became legal at the state level recently and so the parks department is doing a pilot (for which they want your feedback). The pilot includes a maximum 15 mph speed limit for all users, on ebikes or not. This is likely due to concern that people will blast past people on foot or slower or less confident trail users. Unfortunately that’s been happening for some time and in my experience has little to do with whether the person is on an electric bike or not.
But this pilot points out a big contradiction in how we treat speed limits: for a trail, we can just lower all speed limits for all. For a road, we won’t, at least not without studying each road and spending money.