Every day, millions of Americans stand at store checkout counters and make a seemingly random decision: after swiping their debit card, they choose whether to punch in a code, or to sign their name. It is a pointless distinction to most consumers, since the price is the same either way. But behind the scenes, billions of dollars are at stake. When you sign a debit card receipt at a large retailer, the store pays your bank an average of 75 cents for every $100 spent, more than twice as much as when you punch in a four-digit code. The difference is so large that Costco will not allow you to sign for your debit purchase in its checkout lines. Wal-Mart and Home Depot steer customers to use a PIN, the debit card norm outside the United States. Despite all this, signature debit cards dominate debit use in this country, accounting for 61 percent of all such transactions, even though PIN debit cards are less expensive and less vulnerable to fraud. How this came to be is largely a result of a successful if controversial strategy hatched decades ago by Visa, the dominant payment network for […]