

Again, they they are completely different organizations. It’s not a question of simplicity or complexity.
The ECHR looks to address human rights issues with the cooperation of its 46 member states.
The EU is (mostly) a trade union comprising of 27 member states.
The UN, NATO, and WTO also have many European member states and again are different organizations.

The author is Paul Krugman, a little known economist, writes for the papers I think.