If I want butter with salt I can sprinkle it on top
It's to preserve it. Rather than for flavour (though salt obviously enhances that). Remember, the U.K. was the first country to industrialise and that happened long before fridges. It's possible to unsalt salted butter (chop in small pieces, put in a bowl, pour boiling water on and after it's cooled a bit, put it in t( fridge.
The salted/unsalted thing does have an effect on any given country's cake recipes and it's worth bearing in mind when you bake.
Question I have here : does Atch mean fish on Christmas day or Christmas Eve?
In PL, Wigilia for sure. In the U.K., Christmas Day. I've never figured out why people think we all have turkey. I've hardly ever had it at Xmas and frankly it's a nasty meat.
About things you can't get used to, I've never figured out why turkey is dearer per kg than chicken in Poland. I've asked people and they've said that turkey is better. I don't know why they think that since turkey (in Poland where it's all factory farmed very much so, maybe more than the U.K. which has 'posh' turkey and factory farmed stuff) is far lower quality, basically a sort of protein mass full of artificial hormones that was once briefly alive.
Suròwka from kapusta kiszona is to die for with fried fish!
Now and again, in small quantities for me. I'm not a cabbage fan but do like red cabbage and love pickled red cabbage, the crunchier the better. I'm a northerner, so I'd put malt vinegar on fried fish, and put it on from the bottle in that way that northern men always do (google vinegar strokes if you're not at work and are broad-minded).