Desire Paths

I'd think German traffic engineers could come up with a better solution, yet these are everywhere:

The bike paths themselves are desire paths for cars and motorcycles.
To block them off, they put up barriers, but those also block cargo bikes, wheelchairs and strollers, create a collision hazard, and force all cyclists to stop and dismount for no reason.
Of course, they'll be bypassed wherever possible – naturally by cars and motorcycles too, if there's enough room.