>They can't be treated like bicycles because they're too fast but aren't nearly as dangerous as motorcycles.
As a former rider, why? Cars were the most dangerous part, in my experience.
Something that stuck with me from my motorcycle safety course, the speed at which hitting a wall is 50% fatal is 30 mph. Doesn't take highway speeds.
The goal is not to protect the people on motorcycles, who (if we're being brutally honest) forfeited most expectations of safety as soon as they got on their bikes.
The goal is to protect the regular cyclists and pedestrians who they currently share paths with while trying to not make them TOO unsafe.