Yes actually France is very unionised, every big mobilization (except for the Yellow Vests) is due to the major unions with millions of members. Problem is, no mobilization in recent decades (including the Yellow Vests) are linked to a greater political project. Worse than that, the unions all have a syndicalist ideology that makes them refuse any meaningful alliance with a political movement. It somehow allowed them to survive cold war propaganda so I can’t blame them too much, but then they are useless on a revolutionary standpoint.