Norway is not in the EU and is starting NAI to gain access to EU open skies. That is a Flag of Convenience.
Do any of the airlines you named have US based crews? It matters because as long as they don't it limits the pressure on wages because their are only so many Americans willing move abroad. With US bases it perpetuates a race to the bottom here at home.
You still didn't answer my post above? Is it possible for a European to earn what American pilots are currently? If not it's not really a career especially if it's a short term contract. It's a job. And if it can never support a family comfortably it's a dead end one at that.