South Korea is renowned for its digital innovation, with coast-to-coast broadband and a 4G LTE network that reaches into Seoul's subway system. But the tech-savvy country is stuck in a time warp in one way: its slavish dependence on Internet Explorer.

For South Koreans who use other browsers such as Chrome or Safari, online shopping often begins with a pop-up notice warning that they might not be able to buy what they came for.

"Purchases can only be made through Internet Explorer," says one such message on the website of Asiana Airlines, one of South Korea's two major carriers.