I think that's a great question, so I just wanted to throw in my two cents.
There are some matters where co-operation might help. There are other issues for which, to me, there is a key question when you think about global economic activity: Are there jurisdiction-specific remedies that can be ordered? Europe takes its own approach to abuse. It tends to be much more aggressive than Canada. It imposes multi-billion euro fines that are paid to Europe. That doesn't interfere with what they're doing elsewhere. Similarly with mergers, sometimes there's a local divestiture. If one country objects and another country doesn't, maybe you can order a divestiture in the local country and, as it's perceived, that will take care of the competition problem in that country.
You've identified a critical problem, and I don't know that it has an easy solution or any solution. It's a global merger that has an impact across the globe that can't have a jurisdiction-specific remedy. That's a real problem. You can co-operate, but what happens if Europe and the U.S. disagree, as they do frequently? All it takes is one person to say “no merger” and the merger can't go ahead.
I think you've identified a really important problem. It's nuanced, depending on context.