OK, thanks, admin. I guess the legislation (whatever it is) is aimed at the golf cart type vehicles: they're not outlawed because they're not powered by an internal combustion engine, but because they're too slow to blend with other traffic and/or don't offer occupants enough protection in a crash and/or fail to meet other safety requirements.
I don't see a minimum attainable speed requirement in the HTA, but it may be in some other legislation.
Maybe drivers of low-speed electrics could be charged under R.S.O. 1990, c. H.8, s. 132 (1), "No motor vehicle shall be driven on a highway at such a slow rate of speed as to impede or block the normal and reasonable movement of traffic thereon except when the slow rate of speed is necessary for safe operation having regard to all the circumstances." But, still, we're seeing more and more of those "mobility scooters" on the roads in towns and cities, increasingly being driven in (or alongside) normal traffic, and I doubt those folks are getting ticketed very often, possibly because "the slow rate of speed is necessary for safe operation."
It will be interesting to see what happens when (and if) the Tesla Roadster or something like it starts showing up in Ontario. It's hard to imagine what existing legislation could block that sort of car (unless the powerful batteries were deemed to be explosives or dangerous materials under 112 (1)?).