@antijingoist most of the signage does list the routes that stop there, but there are some variants that only indicate a bus stopping zone. Not sure if there is a rule requiring one to be installed near the other (I could see the zone-marker one being used where there's a shelter)

But it is indeed frustrating to navigate the #MBTA's busses without supplementing the signage with a smartphone (or paper maps/schedules if you're a masochist)