Yup. It's also common to get discounts for cash. Some places like pawn shops, used bookstores, junkyards, and other businesses will always offer discounts over published or listed prices for cash, and those discounts are often much steeper than just the cost to the merchant of a credit card transaction, and sometimes are quite a bit more than the choice by the merchant to under-report taxable transactions would account for too. I suspect that in part it's a matter of the business having the money now, as opposed to having to wait until the end of the month to get paid. Plus there's always a possibility of messing up a credit/debit transaction, which can result in having one's account (and all outstanding revenue) put on-hold until the processor chooses to release it.
Credit/Debit works best for large companies where there's little to no haggling, and where the sheer volume of transactions allows that merchant to negotiate good terms with the processor, but they're still at the mercy of the processor as far as account and transaction fees are concerned, and then there's the other issue of security. Target, Neiman Marcus, and PF Changs are all going through that right now, and I don't doubt that it'll get worse as time goes on, and while "pin and chip" cards may help, I expect that someone will figure out how to steal through those too, and the cycle will just continue.
And then there's the personal sale angle. I'm not going to take paypal or have the ability to process credit cards for a yard sale or some crap that I'm selling through the classifieds or craigslist. Given how I'm mainly just trying to recoup something in the process of a sale, adding more hoops or steps will just result in my not bothering to sell junk anymore.
