bum, raja is dead right, when I was in Germany as well as Coca cola dispensing machines they have beer dispensing machines, put in your euros and down drops a half litre bottle of Pils or Helles and you're well away.
At service stations
Also the UK is much more relaxed, most corner stores sell grog and supermarkets have beer aisles interspersed with the baked bean aisles etc. However I think the problem with the Valley etc is not the availability of beer, it's the binge drinking culture which they also have in the UK despite alcohol being more readily available. A lot of the problem is that the drinking occurs as 'pre drinking drinking' where they are half pissed before they hit the Valley Station. Actually at the Station Food Concourse itself when the partying Gen Ys pour off the train at 10pm onwards there's a Mr Liquor store right there, where they could drop in and pick up a bottle of Chardonnay to take to the Chinese BYO restaurant. But it's not well patronised and going on the bare shelves I don't know if it will be there for much longer.
I would imagine that they opened the store with the idea that people coming into the Valley would pick up supplies - fine for those going to a restaurant, but most of the clubbers are in a different category and have already drunk a four pack of vodka blitzer on the way in.
Edit: I work in the Valley and usually exit work after 11pm, and have noticed that the beer of choice on the footpath BYO dining tables in Chinatown nowadays is Fat Yak - my God we live in hope