One reason why they lose less bags is due to the smaller amount carried due to surcharges for baggage. Pax refuse to pay it and cram things into their handluggage and buy the rest at the destination !
You ovelook the obvious in that what FR have done is to force passengers to consider whether they need all that gear to lug around when cutting it in half still makes no impact on the overall enjoyment of the trip.
FR in following Flybe in introducing charges has changed the way people travel and stopped the lets take loads of stuff just in case we need it. A big benefit has been that aircraft don't burn fuel to carry stuff from country to country that stays in a suitcase.