An anecdote: the first time I was in Spain as a kid (touristy reasons), I noticed a 20 EUR note someone dropped on the ground (this was in Madrid). I stood there for a second contemplating. My child brain went "I found something that someone lost => Need to put it in a prominent place so that the owner can find it and it doesn't get dirty" (I was a much kinder individual back then). So I picked up the bill and was about to put it on the window sill of a nearby building when a guy walked over to me and explained in broken english that I should keep it. I looked at him in total confusion, but then he flashed some kind of local police ID at me and explained to me that if I don't pick it up, someone else will, and there is no way to find the actual owner. I will probably remember this for the rest of my life (partly because 20 EUR was a huge chunk of cash for me back then).

ACAB but some are worse than others.