Offer your thoughts or opinion on the input financial query or topic using your financial background.

Why do grocery stores in the U.S. offer cash back so eagerly?
Cash-back also lets the store turn hard currency into an electronic transfer or check, which reduces the hassle/risk of hauling bagfulls of cash to the bank. (The smaller stores I've spoken to have called this out as a major advantage of plastic over either cash or checks. I'm assuming that the problem scales with number and size of transactions.)