For a perspective from within Mainland China — you’d expect these problems to be 10x worse there, but they’re largely solved for most items (on Taobao, JD, and Pinduoduo):

- you can return almost any purchase within 7 days of receiving it, without any reason or excuse, usually with free shipping

- logistics and payments are extremely efficient and low-overhead, meaning everyone is ordering a bunch of options, receiving them within 1-2-3 days, and returning all but one or all, the system is handling this well

- margins are low, competition is crazy, search is AI/image-based, meaning you almost always get an amazing deal, 3x-10x cheaper in nominal terms vs same product on Amazon

- the way Alipay works on Taobao, most consumers are allowed to defer payment until they received an item and decided to keep it, no credit card needed

This only fails with products where it’s difficult to verify the quality yourself and the downside risks are high - most famously baby formula - then you just buy from official brand stores at high markup.