Why do so many West End theatres have a terrible, and very limited, selection of drinks?

I recently saw a few shows in London. Other than “Into the Woods” at the Bridge, every other theatre had a terrible, and very limited, selection of drinks.

For example, I went to the London Palladium to see L5Y. They had no beer on draft, and the only ones they had canned were lagers. I do understand that having drinks on draft is challenging, but why not have cans?

From a commercial perspective this makes zero sense to me! I’m always reading that theatres are struggling financially, but then I don’t understand why they don’t make more of an effort with refreshments? At every show I saw, I would have bought more drinks had there been something available that I liked… Therefore, theatres are losing out here!