I suppose that it's cheaper to keep people from using the roads than it is to make the roads safe.
I drive a school bus on all of the roads that are involved in the proposed ban. DD in particular scares me because it's fairly high speed traffic, there is no shoulder at all and significant drop offs over much of it's length. There is a project on the books to install shoulders on the roads in question but they are only planning to widen them by a couple of feet.
Frankly, I question the purpose of the proposed ban. I'm thinking it's real motivation is to remove obstacles to faster auto traffic. There are cars going off the road in these areas all of the time. If safety were the prime consideration I would think that imposing a lower speed limit would make more sense.