As a no longer alcohol drinker here's how I consider non-alcohol drinks pricing;
Yes a non A drink may cost slightly more than it's equivalent but when I drank alcohol usually I would drink more than one, when I'm drinking sparkling water, tea, coffee I tend to stick to one.
I've paid £4 for a fizzy water in a beautiful London hotel bar, sat with people buying £16 cocktails. That drink was the only one I needed, and the venue was stunning (with musicians playing to requests).
If I'm in a pub to see a live band I may only buy one or two drinks all night, these are soft drinks. I tend to arrive hydrated and dont need to be constantly sipping - the pub aren't making much from me.
Ok may not always be somewhere as salubrious as the London venue but the principle is the same. I'm not downing several or many, followed by alcohol fuelled kebabs, or whatever. And the cost of my drinking was more than the price BUT a normal drinker only having one may differ in opinion.