It's simple. I did not know for certain where the bag originated, nor did I know for certain what the objects in the tiny ziploc baggies were - I assumed they were rock cocaine - only place I've actually seen such was in news pictures. I wasn't interested in finding out for sure, nor was I particularly eager to call the cops and say, "Hey, I found this stuff and think it might be drugs." Not too mention, previous experience when I found a bank bag and turned it into the cops wasn't very positive. They refused to open it and give me an itemized receipt, yet when the owner showed up at the cop shop to claim it, the bag had been opened (breaking the lock) and no cash remained in it - he claimed it contained over $2,500 in cash along with the checks, and threatened to sue me. Fortunately, I took a pic of it lieing on the police station desk, which was identifiable as such. Lock intact.
My experience dealing with cops tells me the less I need do so, the happier I am. Customs and EPA enforcement are quiteanother matter - that's about a level playing field for all.