We had a card surcharge ban bought in a few years back. The shops aren’t allowed to charge extra, and unless you’re employing family members or not declaring the cash (and for a lot of small takeaways, it’s probably both of those) it probably works out more expensive to handle the cash.
It’s mostly small places that don’t. I think they started during covid so they didn’t have to physically take anything from the grubby customers, and found they didn’t lose much (if any) business over it.
Cash still costs money to handle, either for the time or wages of taking it to the bank, or paying somebody to collect it every day.
I guess it helps that contactless payments are now ubiquitous. Practically everyone has a phone, and readers like SumUp and Square can be had for a few quid.
But then there are places that still only take cash, because it’s easier to hide that from the tax man.