I would agree that the theft issues we had were all on AA in SJU. There was once however a TV special where they showed video of baggage handlers going to work and from work for all airlines. Nothing going to work being carried. Leaving work most had full garbage sacks in their hands. Could only happen if airport security looked the other way. JFK seems to have similar issues that come and go but not as brazen as SJU. What was really interesting in SJU was how they managed to steal out of carryon bags on the ATR’s where you handed the bag over at the aircraft to go in the front of the aircraft. Found out later they were searching the bags in the hold where they kept a empty bag and transferred stuff to the empty bag to be removed later.
Nothing valuable should be placed in checked bags!
G