well, i've seen U2 in the US, in Canada, and in Europe, and the best crowd i've seen was in Philadelphia. the people in my section knew all the words to both "an cat dubh" and "yahweh" -- that's a real fan. i think it comes down to the fact that in certain cities with a highly monied elite -- like in NYC, SF, Paris, London, etc. -- you are going to get lots of people in the crowd who are there because they were connected enough to get this year's hot ticket, as opposed to being big fans. for pete's sake, at the DC show i saw women there wearing pearls. ugh. however, in a more blue-collar town, like Philadelphia, like Pittsburgh, you are going to get the diehards who are damn well going to get their money's worth.
i think the Chicago CD looks great, and visually it might be their most beautiful tour ever, but it is a little emotionally empty, but i think that's the band's fault. Bono's voice was much better at the other Vertigo concerts i saw, and my brother was at the May 9th show, and he said it was easily the worst U2 show he's ever been to -- though he said the 2nd round of Chicago concerts in September were AMAZING.
so, before we toss out generalizations about entire countries, let's keep in mind that, at the end of the day, it does come down to the band.
i also would like to say that there are many people out there who make blanket statements about the US that would be 100% unacceptable if it were applied to any other country on earth. this is not to support, in any way, ZooMacPhisto's silly comments, but simply to say that casual, unthinking America-bashing isn't any more correct than casual, unthinking New Zealand/Netherlands/UK/France/etc. bashing.