All transport modes impose some kind of externality. Trains need marshalling yards and a permanent way, and have a really serious ongoing maintenance budget. For public modes that’s planned in: bus routes get more roadwork, stops get isolated from parking, it’s accounted for.

For *private* modes like these there’s every incentive for companies to offload the externality (parking) onto the public, and specifically the spaces of the people least likely to be able to step over a tangle of bicycles.