Back when I worked for an airline, there was a huge warehouse where all luggage that could not be re-united with its owner was stored. Every now and then we would take a little "shopping" trip through the warehouse and see if there was anything we could use.

Some of the stuff abandoned (apparently) was pretty bizarre, and often expensive. I know for a fact that the airline made mighty efforts to return it, but if the pax never filed a claim, did not mark the bag/package, and in general did not seem to care about it, what are they supposed to do?