Naval Group don’t need subsidies to be competitive. They’ve got the whole front section of the sub already designed and coming off a hot production line, and the design of the back section (the conventional propulsion modules) already paid for by Australia. They have the largest scale in terms of sub production facilities and order book, and the lowest design risk compared to the others as they don’t have to scale up a smaller design.
Those are significant natural cost advantages when bidding, which the others don’t have. Nothing to do with being partly government owned (indeed they still must turn a profit just like any private enterprise - otherwise Saab, TKMS or Fincantieri would all be able to sue in EU court for illegal subsidies).
For Saab, there are some parallels to their challenges selling Gripen against larger US and European fighters. If you don’t have scale, it’s hard to compete. What Damen-Saab seem to be hoping for is a political decision to override what seems like a fairly legit competition.