Its fine in Europe, but you still see people in cages get all bent out of shape. Just like in Michigan, when there is a closure in a lane, people can't just merge, you always get one asshole that has to be the policing person and puts his car half way in the lane to block people. Like they are the designated asshole.
I think it would be fine "IF" people accept it. How many times do you see people swerve to stop you from passing them? I see it here often.
I just choose to not ride in heavy traffic if I can help it. Even in a cage, I try to avoid it. People are just too stupid when they get stuck in traffic.