We’ve had similar ones but unless it’s just my shitty memory that’s a new bit of info for me. Cheers. It does seem a US quirk as they’ve never appeared like that in the UK or while I was here in Malaysia before digital days.
(Yes I kind of assumed a ‘mystery shopper’ approach to the other thing, there’s not really any other way to do it. Maybe now with digital projection they can send some message back but that doesn’t solve the tickets sold check).