Its seems to me that the principle reason that they are refusing to allow people to bring food and drink with them has nothing to do with safety, but a greedy desire to sell your their stuff instead !
I can recall attending the Royal Albert Hall in the heatwave of 1989, to see the Bolshoi Ballett. I had a small bottle of water with me but was told by an official that I wasn't allowed to drink from it, as "food and drink" wasn't allowed in the RAH.
But I could look down on the more expensive seats and see loads of champagne and smoked salmon sandwiches being scoffed down !