Cash is also preferred in food service, because it's easier to cheat on taxes. When you're paid a tip in cash, with no paper trail of what that amount was, the reported earnings on the tax form is merely a suggestion to tell the truth.
My favorite local restaurant has a 3% card surcharge and a 10% cash discount, so like, 14.4% card surcharge. Yeah, probably for tax reasons. (This isn't why they're my favorite, their food is just really good.)
