As Walmart and Amazon look to boost their margins through digital media sales, the two retail giants are sweetening the deal for potential advertisers.The former announced last month that its warehouse club chain subsidiary Sam’s Club’s Member Access Platform (MAP) is launching display ads within its Scan & Go feature, making it the self-proclaimed first retail media platform to introduce advertisements through a mobile self-checkout app. The goal is to offer advertisers a way to reach consumers at the high ...