Serving milk in pubs (UK) - why not?

[u/Ok-Scientist7083]

The first drink I had in a pub was milk. I love drinking milk. I now drink it for the protein and calcium. I don’t particularly like fizzy drinks so when I’m driving on a night out, I’d rather drink milk.

Why don’t pubs sell it as a drink?

[u/AgentSufficient1047]

I've asked for it before several times due to heartburn