Every country involved has industries which won't allow this. For example, all the countries in the G8 have agricultural sectors which will not allow elimination of trade barriers.
So, even if you want "free trade," you start with each country's list of stuff where there is not going to be free trade, and move forward from there.
It's not really my idea, it's what the larger countries basically did starting in the eighties and early nineties when free trade ideology was quite strong, leading up to the creation of the WTO and EU and so on and so forth. What you see today is the evolution of that starting point that you like...
Every country involved has industries which won't allow this. For example, all the countries in the G8 have agricultural sectors which will not allow elimination of trade barriers.
So, even if you want "free trade," you start with each country's list of stuff where there is not going to be free trade, and move forward from there.