No offence intended, but although Wembley was sold out twice it was quite obvious large numbers of seats were empty. I have a stadium-wide photo of the Saturday night and there are literally thousands of empty seats. That just contributes to a poor atmosphere IMO
That said, I still want them to come back to the UK.
I think that's true for all shows these days, whether officially 'sold out' or not. The days of Live Aid-style seas of people and unbroken crowds in the stands are long gone, mostly to do with health and safety etc.
Purely as an interesting comparison, here's some attendance figures for concerts that have taken place in Croke Park, Dublin - all shows were officially declared to be sold out, yet figures vary because the maximum capacity clearly differs depending on the nature of the event staging, and inevitable health and safety considerations:
U2 (2009) - 243,198 equates to 81,066 per show
Take That (2009) - 77,988
The Police (2007) - 81,640
Robbie Williams (2006) - 78,905
Bon Jovi (2006) - 81,327
U2 (2005) - 246,743 equates to 82,248 per show
The stadium capacity is automatically reduced for all-seated concerts (to around 64k), with Neil Diamond and Celine Dion being recent examples. But, having been to several of the above concerts, I can verify that there were gaps in the crowds, and - objectively speaking - GA crowds that didn't fill the available space.
I think that stats like Billboard Boxscore go on the raw financial data of tickets available versus tickets sold - however, a ticket sold doesn't necessarily mean that the owner actually turns up on the night. It just means that, somewhere along the line, it's been paid for by somebody. If that original purchaser is a scalper who can't sell it on, or someone who's just unable to attend for whatever reason, the transaction is logged but the seat is empty. For example, at the 'totally sold out' U2 concert I went to on 25th July this year, there were four empty seats beside me for the entire show. Those seats were paid for, so it's a shame that their tenants didn't show up. (Or found a better vantage point perhaps? But the point remains valid that, unless they somehow made it onto the GA area, there were still seats unaccounted for somewhere.)