I see these every time a bicycle path intersects with any kind of car or train infrastructure. It just seems really patronizing, as if we’re not capable of slowing down without getting off the bike; it also shifts responsibility onto the cyclists if there is a crash based on something arbitrary (mounted vs dismounted).

Yeah I can’t even imagine. The bike lanes were I am at are on the street and constantly intersect other roads that also have other bike lanes. It would almost be funny to put one of these up as a joke but then I would worry some car head would think its a good idea.
Yes, it’s clearly some car-brained suburban shit from people who’ve never had to ride their bike to work.