as a long-time AZ rider (4yrs-20k+ miles),,,
I have tried to keep aware of legalities regarding MB's
state law clearly says less than 20mph, and that is easily broken by coasting
I believe the problems in Tucson are because there are so many bikes there
(not all, or even most of them are being ridden responsibly), that they drew bad attention to the cause
I have been ticketed under a local by-law forbidding go-peds, mini-bikes, etc..., and beat the ticket in court by proving I fell under the state's definition of a MB
after all this time, and being seen so much (I take my grandkids to/from school every day), I am well known and don't get hassled anymore
I even went the pro-active route, and befriended the mayor and a councilman here (if anyone tries to make a local law against MB's, they know at least one person who is a legal/responsible rider)
btw...they both really dig the girls and their trailer
please check out the pdf attached from tucson's web site (dated Sept 2006)