you do know if you "keep" the money, you are legally guilty of robbery as soon as you pick up the bag..
In 1981 a man pulled out of a parking lot in Tempe AZ and as he entered Hayden road, a bag flew off the roof of the new corvette. Another motorist seeing the bag fly off stopped and grabbed it (coincidentally another corvette)..
The second vette immediately turned the bag containing $52,000 over to the Tempe Police dept. Unknown to the second car, police were already looking for him as an APS truck doing maintenance on a line witnessed the entire event and logged the license plate of the second car..
it was my dad that lost the money, he pulled out of Big Surf after laying the previous days receipts on the roof of his car... I know he gave the good Samaritan a good reward..