I want to say it's 20 or 25 mph in florida, (think ez go's out here) and you need the licenses / seat belts etc. Bikes id imagine to be the same, however they'd be much more dangerous at those speeds. At least the ez go you kind of have some protection around you, even though it's still pretty flimsy it's better than nothing.
Depending on where you live the cops may or may not hassle you, and a LOT depends on your attitude too. The only time I really seen the cops get shitty with someone was when they got an attitude, or thought they could run. (running is going to get you an ass beating too when they catch you, just as an FYI) Otherwise it's generally an, 'ill be back in 20 minutes, you boys better be gone' type thing.
Their attitudes about the E bikes is, if they are not being jackasses, leave them alone, if they are on the bike trails that's fine IF they are behaving themselves, but if they are pissing off the joggers then its time to have a talk with them. to classify as an e bike it BETTER have pedals on it, if you are on a bike trail and it don't have pedals, then you are in a world of misery when they grab you.
Works pretty good out here, it really is not a problem with teens terrorizing people. Out here in the burbs, the neighbors will whoop your ass just as fast as your dad if you act up, so ... they really don't.
Aaron