It is not checked in France, ever, at all, and TFA is about French TGV. It is true that it is "checked" in Spain; I experienced it this summer while going from

It is not checked in France, ever, at all, and TFA is about French TGV. It is true that it is "checked" in Spain; I experienced it this summer while going from Sevilla to Cordoba. However the check is (in my experience) quite superficial; also, as it creates long lines of people that get upset that they may miss their train, it is expedited and many things do not in fact pass through the X-ray machine. And finally, it is not checked on all trains; we were checked from Sevilla to Cordoba (the train was going all the way up to Barcelona) but there were no checks on the return leg. So, while it would be trivial to bring bad things aboard a train in France, it seems that it wouldn't be difficult in Spain either.