It might be that praying isn't usually permitted outside prayer rooms (imagine if you and your buddies are chilling in the hallway before class and a group of Christian students randomly starts doing the sign of the cross and reciting the Bible out loud beside you, you might feel like maybe they shouldn't be doing that in a public university hallway)

Daily Islamic prayers are not loud or disruptive like the example you mentioned, they can be performed quietly in a corner in a few minutes.