When my state made motorcycle helmets mandatory, I actually moved to a state that didn't. My dirtbike experience consists of accidently riding an old fashioned doodlebug on grass when the throttle stuck wide open. I still have a scar on my ankle from that. Well, I guess I have a little more experience than that. I also rode 3 wheelers for awhile back when they still made them. They were called ATCs, as I remember.
I was living in California at the time and they didn't have a helmet law until the very late 80's (I think.) I moved to Oregon in '90 and they had just passed a helmet law.
Soon after that the state legislature repealed in it and the dem governor vetoed the repeal, every time.
I've never ridden a three or four wheel ATV, only two wheel enduro and motocross bikes from 125cc to 500cc.
I've owned 8 off road motorcycles from 1965 to 1983 and 15 street bikes from 1948 until the present.