As others have pointed out in other comments, accepting cash has its own cost. I leave it up to business owners/managers to decide how much it costs them and if they want to offer me a better price if I pay by card or by cash, and if they make the policy clear, I am more than happy to determine which payment method to use based on their own pricing policy.

Unfortunately in many cases they are also figured into the prices cash customers pay.

That's implied by "every one".