I'm happy with the rounds system, but a question re expectations

[Honds]

All my life, social occasions have meant rounds. It's probably old fashioned now, but it's the way things have always been done in my social groups.

I'm aware sometimes I'll have paid more than my share, and other times someone else will have paid more than they should, I'm sure over a lifetime it all comes out in the wash.

Recently I've cut right back on my drinking. The group is generally aware of this and will jump in before I buy too many drinks. I.e someone will buy a double round when it gets round to me again, but either way I see the cost of the round as the cost of the night out, rather than directly related to the drinks I've had, and soft drinks are expensive anyway. No one is looking to rip anyone off. Usually if I've driven because I'm not driving and offered lifts, I wouldn't be expected to buy at all.

I have realised that my preferred non alcoholic drink is plain soda water. I don't want the fake beers or sugary soft drinks. Soda water is usually (but not always) free.

Would people expect me still to step up for a round, when they've been fetching me soda water all evening?

In practice I don't mind buying people a drink, I just wonder what people would expect. My evening would be "free", but I don't think you could spend all evening in a pub if everyone wanted soda water and free drinks all evening, so the cost of the others' drinks is subsidising me iyswim.

I don’t drink alcohol and me personally, I opt out and just get my own drinks, because I literally can only drink about 2 fizzy drinks anyway before I feel a bit too bubbly inside.

If your drinks are free, surely people will just get you one when they get a round. If you want to on occasion, sure, offer to buy a round, and see it as the cost of being out. I wouldn’t do it often if your drinks aren’t costing anyone anything, but it’s a nice thing to do sometimes, like if you’re out celebrating someone’s birthday. Really everyone benefits from you not drinking as it’s cheaper overall.

I think you're right that the issue is that the venue makes no money so not viable for everyone to do it - maybe make a point of saying you'll drop out of rounds as your drinks are free, but you'll leave a decent tip at the bar.
You don't seem like you're being tight, and the bar staff win too!

I wouldn't expect you to buy me a beer if you're on soda water, but I can guarantee it's unlikely to come out in the wash if you've got a group drinking different drinks.

Basically the wine, spirits and cocktail drinkers are heavily subsidised by the beer drinkers if they stick to rounds unless in the unlikely event that those who have the expensive drinks acknowledge this and buy more rounds. I don't have wine, cocktails or spirits while out due to the cost, so it does rankle when I end up paying for others to have them.