What is to stop a zealous idiot filling a flask with petrol or acid, or worse, and lobbing it into the crowd. The ban on flasks is appropriate to the risk. ie low risk but potentially high impact.
So what was to stop them doing that at the start of this season. Or last season. Or the season before that?
Why is it only this week that bottle tops are now classified with knives as too dangerous to allow at the Amex?
It is illogical. It makes no sense. It has stuff all to do with security or those restrictions would have put in place from the day the Amex opened. It is purely financial; make it difficult for the buggers to take their own drinks into the ground then they will have to buy ours at inflated prices having stood in lengthy queues to be served (eventually) by a moron!