why is it that once something is left on a plane, that it is immediately assumed ground staff steals them or doesn't return the item to Lost and Found. I have been in many seats after a plane has been cleaned and found a lost article from the occupant on the previous flight, or even before. This isn't just on AA, but on UA and NWA too (which I often commute to/from MSP)

I always hand in the stuff to the Agents and make sure they in turn call their local Lost and Found. Someday, you should go to an airport Lost and Found and see all the stuff that has been lost. Too many things go unclaimed. Don't always assume that airline staff are thieves, there are plenty of Pax that steal as well.