Seems to me the argument is about process, not about end results. The regulator wanted developers to have a choice of payment systems. They got that from Apple, but apparently that's not good enough. They only want one app submission, not a separate one. If the NL got their way, why would they care how it happens? The user is going to see whatever payment system the developer wants to use, so it's a win for the NL. Why the continued fines? Seems to me there's more to the eye here.
My own opinion is that the NL shouldn't care if developers have to submit a second app for the NL only. They should only care about end result, not process. Are they trying to force this on the rest of the world? Apple is requiring a separate app so no one figures out a workaround in the rest of the world. What's the real reason the NL doesn't like the solution Apple presented, even though it gave them what they asked for?