Passive perception at pnp DND dont force a roll actually. Any good DM will know what the passive perception of his players are and if he would have to ask what they are players tend to metagame until they find whatever it is that they are in danger of missing.
Im all in favour of not showing the roll at all, because I notice the same behaviour on my part xD it doesent feel natural.
Also if you know a roll is coming up because you already saw 1 person roll and fail that testyou can buff your guys to raise your odds of passing that check. Which kinda goes against the whole 'passive' part of passive perception
