Saw this at a local Russian market, they know what’s up. Really need “Pay with #bitcoin and save!” versions of this sign. 
Discussion
That’s the processing fee that visa charges merchants, not buyer. But some merchants pass it on to buyers instead manually.
Reasons merchants have told me in the past they don’t support bitcoin:
1. Volatility compared to denomination in fiat.
2. Treatment for tax is uncertain.
3. General distrust of crypto, and Bitcoin placed in that basket.
4. Many govts have made it illegal for business to accept Bitcoin as mode of transaction.
My thought was that since this was a Russian market they may be encouraging their customers to use cash due to the recent experience their country had being cut off from the global financial system. If so then bitcoin would be an even better way to receive at least some of their payments. Or they could just be trying to keep their prices low by not baking in the 3% credit card fee. Either way it’s the sort of business that may be open to accepting bitcoin.