The surge in pandemic-fueled online shopping has created a new urgency to solve a decades-old problem: returns. Companies such as Walmart Inc. and Amazon.com Inc. are telling customers to keep unwanted items. Some retailers are introducing virtual dressing rooms and made-to-measure clothing so that shoppers keep more of what they buy. Others are scoring shoppers based on their return rates, much the way credit-ratings firms tally consumersâ creditworthiness. Behind the push is a painful economic reality of e-commerce. The share of online purchases that are returned averages 30% or higher, depending on the category, three times the rate in physical stores, according to industry executives.