UK here - I wouldn't say cash bars are the norm here - I think what can happen is that you have the formal reception, where drinks are generally paid for, but it is also quite common for that to be followed by a bigger, evening party, where there *may* be a cash bar.
We don't have 'cocktail hour'. My experience is that wine is generally served at the reception (or sometimes, wine and beer) plus Champagne (or other sparkling wine) for the toasts.
*If* there is a separate evening 'do' and *if* that has a cash bar then of course people are free to buy spirits as well as wine or beer.
I can't think of any wedding I've ever been to where there was a cash bar and the couple only provided soft drinks. I have been to a couple where there was beer and wine available in the evening but the venue also had a bar open so if you wanted shots or cocktails or a different brand of beer you could get it.
When my cousin got married, (immediately after graduating) they had a low cost wedding. They didn't have a cash bar (couldn't have had if they'd wanted, the hall didn't have a liquor licence) but they did leave a box out and mention (once) that if anyone wishes to give a contribution towards the cost of the booze it would be welcome. There was no pressure and no one monitoring what you put in against what drinks you had. This was at the evening reception, when a lot of their friends (mainly students and recent graduates) came.
Those of us who were there for the whole thing got served wine with with our meal.