Of course, they need to get it right so they dont completely reduce sales by a huge amount - bit like riding a unicycle on a tightrope - its a tricky thing. If there was competition from others near the Amex like some other stadiums, the prices may be lower to attract customers, but seeing as...
Its hardly a huge increase and its £6.75 with the 10% cashback, so if you buy a pie and a pint every match for 10 games, you get a free one effectively.
God help us if we ever reach the Premier League as prices for everything would be higher. Should go to an Olympic event or The O2 to see some...