Thats ridiculous. Motorcycles?? A thing that weighs hundreds of pounds, with a full gas motor, in a lane where most users are on a ~25lb bicycle, including kids? GTFO
Not to mention the difference in bulk size, its already often difficult to pass slower people AND KIDS, when theres people coming the other way.
Theres also a large difference in acceleration. Mopeds/motorcycles can get to car speed VERY fast. No average bicyclist is getting to 20mph off a start anytime soon.
Those lanes are to offer safety from larger vehicles that also go faster. When those vehicles are in the same lane, it sacrifices that safety.

People forget bike lanes are also good for kids, who have NOT gone through the training to learn to drive. So they don't know all the same rules drivers do, nor do they have the road experience. That makes it a huge discrepancy of rider, not just for the physical vehicles.