I could be wrong of course, and it could explain why they don't work so well, the system is essentially Magnetti, but if they decided to use other parts in the system, it explains a lot. However, IIRC we never replaced a MAF sensor in the 6 years I worked at Coupers.
OTOH it doesn't really surprise me, Fiat, as the parent company, purchase components from whoever can manufacture them to the price they want to pay, rather than to meet a specification (and I do know this for a fact) - as do quite a lot of other struggling (and deceased) marques.