Er, excuse me.
The Commission has a mandate to negotiate with the US, and also the 'horizontal mandate' which obliges it to get rid of the 'nationality clause' in around 2,000 bilateral treaties which currently restrict operation on a route from country A to country Z, to airlines of countries A and Z. From now on, if country A is an EU member state, then the treaty must be revised to read 'countries A-Y', being the 25 EU members.
Country Z (the poor non-EU state at the other end of the route) is going to say 'Yes, OK' isn't it? The Commission is going to say 'well, you have no option other than to say Yes, because that is now EU law'.
Welcome to planet Europa, they do things differently there.