I think the difficulty of enforcing complex regulations is the problem. Most trails are meant to get pedestrians and bicyclists out of traffic. Most of us don't want mopeds zooming down our trails - and I've seen it in my part of the country. At some point an electrified bicycle becomes a moped and drawing the line is not simple. Wherever you draw it, someone will be upset. At the risk of getting pounced on, I have some sympathy for the park and other officials trying to thread this needle.