LONDON :France's crackdown on Shein over childlike sex dolls and banned weapons is exposing a perennial problem of online marketplaces: failing to properly police third-party sellers and block sales of counterfeit, illegal, dangerous or simply offensive products. Online marketplaces - platforms that let multiple vendors display and ship their goods globally - have surged over the past decade, with Amazon, Alibaba, Temu and Shein generating massive revenues by offering consumers a seemingly