Actually, that is exactly what happened in the case of all of the carriers that were acquired by Lufthansa Group. They did get into Austrian, Brussels and Swiss not only to get the market, which in the case of Brussels they are now starting to give up. They did get in their to use the much less strict labour laws in those countries. And even used illegal tactics to lower those T&Cs even more. Funny enough, they T&Cs at those carriers are around half or less of what their Lufthansa counterparts earn, and in doing so they put massive pressure on Lufthansa mainline as well, which has just last december been forced to lower their own T&Cs by roughly 15% in the best time for the airline ever. Flags of convenience right there with very real results. Of course, even more so through the pressure of Eurowings which has even worse T&Cs and is mainly based on an austrian company, expressively build to avoid german labor laws, and Brussels who is employing nowadays nearly only contractors on the former Ryanair model.

What NEDude is referring to is of course the fact that Norway is part of the european single market (with absolutely no say in the rules of that market) and for aviation therefore part of EASA. It has to follow all the EU rules, has to pay for access to that market, and can not vote on those rules. Why the heck they do that, having to follow rules they cannot influence, is beyond me, but it works for them.