That's exactly it. In the park I mention above, the street next to it is 25 MPH, has sharrows, and also has a very wide pretty much unused paved shoulder as we

That's exactly it. In the park I mention above, the street next to it is 25 MPH, has sharrows, and also has a very wide pretty much unused paved shoulder as well. Except for ignorance, there's no reason for eBike riders to be using the only-about-two-person-wide sidewalk. In the past the speed came with skill which developed through experience. Now that speed is often at the press of a throttle (or setting the assist to high) there are more folks at high speeds without the developed skill or etiquette. Heck, at one of the local parks that I work with (volunteer cycling advocate who develops trail systems), they are trying to figure out what to do about eBikes on their paved walking/running/biking loop which parallels the park road. In the past the mixed use was fine, as most riders on the loop were going slow; families/kids/whatever and coexisted just fine with walkers. The faster riders would be out on the road, going roughly the same speed as the cars. Now that eBikes are becoming popular, the less-experienced folks are sticking to the path, but at higher speeds, causing issues with the walkers. Walkers being clipped by bikes is not unheardof on these paths in the past, but it's becoming much more frequent now that the walker-rider speed delta has increased. (For reference, ~8-12 MPH was common for human-powered riders on these paths. eBikes roughly double the average speed.)