Honest people do need to be kept honest. Even the most saintly can be tempted.
If you found a twenty on the floor in an abandoned alleyway, would you hand it in to police, or would you steal that money?
If your first thought was "It's not stealing for such a small amount", or "It's clearly been abandoned, so it's ok to take it", then you're the target audience for being kept honest.
Your other point is spot on: the aim is to increase the friction of entry and raise a mental barrier in the mind of the subject which results in an outcome you would prefer (no break-in).
>If your first thought was "It's not stealing for such a small amount"
Well, actually... where I live, it would not be stealing for such a small amount, given that you don't know who lost it, and it was found in an abandoned alleyway (and not say, an office, store or station etc. where it could be handed over to local personnel). Had you said fifty, the situation would've been different.</nitpick>
Agreed. The amount is right on the edge of legality. Should you report it? Should you make an effort to find someone to hand it to? If the first shopkeeper around the corner says "Could be anyone's. Keep it" for a fifty, does that constitute a reasonable search for the owner?
If you found a twenty on the floor in an abandoned alleyway, would you hand it in to police, or would you steal that money?
If your first thought was "It's not stealing for such a small amount", or "It's clearly been abandoned, so it's ok to take it", then you're the target audience for being kept honest.
Your other point is spot on: the aim is to increase the friction of entry and raise a mental barrier in the mind of the subject which results in an outcome you would prefer (no break-in).