It's nothing to do with the tour really, logistically you have to get the gear around.
More about doing a gig in the states, flying straight back to UK for a day, back to USA, back to UK, back to USA...... If you do that 30 times over and back the Atlantic on your own when touring the states you're creating an incredible carbon footprint on your own.
That then increases climate change which subsequently affects the poor more then the rich; conflicting with fair trade which looks at the other perspective!
That was the article's gist, must find out where I read it. Just putting the thought out there!