Abroad, it's common for restaurants to bring credit card readers to the table when it's time to settle the bill. In addition to giving me peace of mind, this feels more efficient and makes the process of leaving more predictable. The main downside for me is that someone is watching me determine the size of my tip, which is slightly uncomfortable and often guilts me into leaving a larger tip than I would otherwise.
While unlikely, I worry about rogue staff members copying my credit card number (and magnetic strip) when it's out of sight. I wish credit card companies would provide incentives for transactions to be processed in front of me. By treating these out of sight transactions like card not present transactions (i.e. making them more expensive), businesses would quickly adjust their practices, reducing the risk of fraud.