Criminals might be deterred by knowing that people definitely get arrested in a certain location, because, say, they've seen it themselves, or because they see a presence of law enforcement, or because they innately sense its a high status environment where law enforcement response is to be expected.
A criminal seeing a sign might conclude that the sign is actually telling them that no immediate law enforcement response is likely.
For example, in London, you dont see CCTV signs in the shops along Sloane Street (super high end retail) but you definitely see them in Primark (very ordinary store, like US Kohls).
Wonder if there are any studies on this?