I have been testing a theory. When I check in and show my UAE driver's license as ID, my bag is opened 100% of the time (5 or 6 times now). When I show my Nevada driver's license as ID it has never been opened. With my passport it is opened about 50% of the time.
The only thing that has ever gone missing is a small ziplock bag full of about $2 in US coins... they left my UAE and Qatari coins from the same bag.