If it became completely outlawed on the railway, perhaps I'd agree, but ultimately this is just a business/organisation making a decision about what behaviour it's happy to tolerate. Nobody is stopping you drinking elsewhere; they're just asking you not to do so on their premises. Drinking culture on trains was a problem long before the pandemic ever happened and I think it's a valid concern.
Operators wouldn't run dry trains if they didn't think they had an impact. Nevertheless I do see your point here, and you're absolutely right that someone quietly enjoying their journey with a drink does no harm, but I just don't understand why it's so important that the drink contain alcohol.
If passengers want to consume something alcoholic purely because they dislike all other drinks, that suggests to me that there's a serious problem in this country. If that's not the case, and they do like other drinks, there are infinite alternatives available to them that they can enjoy instead. Soft drinks (and non-alcoholic alternatives) do not alter your behaviour or inhibit brain function in the way alcohol does, so it seems utterly reasonable to me that it would be restricted in certain settings, not least a busy railway. If someone were drinking on your morning bus to work, I suspect you (as in, most people here) would find that inappropriate. Why is it less so on a train? If drinking is important to you when travelling, you have the choice of other options (including on the railway on certain routes, such as with LNER).
Perhaps I'm being ungenerous here, but it feels like people are just chafing at the expectation that they adjust their behaviour slightly. It seems very over the top to frame this as an attack on fundamental human rights, particularly given that "the right to drink booze on trains" is not one most human rights lawyers would recognise!
