Retailers must improve their mobile transaction experience and move away from a “card-based experience” if they want to avoid losing consumers at the checkout, according to head of retail at PayPal Rob Harper. Speaking at the e-commerce expo at London Olympia this morning, for which The Drum is media partner, Harper citied recent research, which found that in 2013 UK businesses lost £1.5bn in mobile commerce sales, with payment friction cited as the leading reason why shoppers abandoned the checkout process on a mobile device.