In some cases, and especially if much of their takings are still in cash, it makes sense to pay wages in cash. In every bar I've worked in over the years I've been paid weekly and in cash. Cards are certainly more widely accepted nowadays (moreso among younger people), but most transactions in my local are still in cash.
I remember working in one bar that was very much on the fiddle. Drink prices were 100% of what the till said, the tills weren't in view of the customer, and cards were very much not accepted. There was a handy cash machine on-site which was free to use as part of the fiddle too!
The owner was a good bloke though, it was nothing uncommon for him to throw 50 quid or even more into the pay packet if there'd been a good week.
I remember having a chat with him over a beer, and he said straight out that he'd rather chuck extra money in people's pocket than pay the taxman. He was getting away with it, because the drinks were absolutely extortionate. They made all their money from corporate events, so it was actually a brilliant job: you'd get your normal (taxed) hourly wage, plus usually decent tips from the corporate types who liked to show off, plus whatever extra you got from the boss. I remember working it out once, and it came to well over 10 quid an hour: and this was in 2005!
Mind you, the clients were appalling.