What’s so good about having a tin of beer, which can be drank anywhere, inside of a moving train? Trains in this country are mainly shit, just not a nice place to drink.
Also you’ll need a wee, and going for a wee on a train is less than pleasant.
If I see people drinking beers on the train before eveningtime, I’m wary of them. They’re going to start doing loud shit bloke banter and disturb me trying to read comics.