In the U.S., French arms have been a much neglected area for collecting and research. I suppose there are many reasons, but the fact is that German, British, Swedish, Italian, Japanese, and even Russian weapons are well known, while contemporary French weapons are uncommon.
It can't be from lack of quantity; France has always had a large armed force, with an army second in size only to the German. Whether French weapons were lost/destroyed in war, were destroyed later by the government, or are being kept in storage, the fact is that relatively few have appeared on the surplus market. Another factor is that French military weapons are, to coin a term, "different". They are just not what Americans want in terms of sporting rifles, so they are curiosities, of interest only to the few who collect French arms or who want them to fill out a general military collection.
Even French commercial arms are rare in the U.S. Only Manufacture d'Armes d'Pyrenees in Hendaye exported significant quantities of pistols to the U.S. Most MAB guns sold here were police surplus, most from countries other than France itself. Manurhin made thousands of pistols, but most of those were sold under the Walther name, and the French source concealed.
Maybe it also has to do with the often prickly relationship between the U.S. and France. Perhaps Americans, given a choice, would prefer to buy arms made by a known enemy, China, than by a sometime "friend" like France.
Jim