Wish is in a very unique segment of apps - cross-border B2C e-commerce. AliExpress is their closest competitor. Last year, a vertical-specific competitor called shein.com also had a hockey-stick growth in uptake. Doing cross-border commerce for long tail, unstructured assortment is extremely hard, specially if you are doing it across categories like Wish. I have tracked the evolution of Wish - product, design, business, seller functionality - for 2+ years now and what you see now is not their MVP in any sense.
Wish provides mom-and-pop sellers access to the global consumer. In addition, the global consumer is mesmerized by their insanely simple and addictive UX and UI. The main challenge with unstructured assort is how to make it all discoverable. Wish incorporated basic but “smart” personalization from the get-go in their product. Sources of revenue are seller services, %age of marketing spends from sellers, CPT, etc. I can see several incremental sources of revenue for VAS to sellers (eg: photography services, predictive product trends, etc.).
At the very core, you are confusing convenience (Amazon & Taobao’s of the world) with having a wide assortment (the Paytm, AliExpress, Lazada’s of the world). Amazon is unique in having both. Wish is about assortment. They do not promise convenience and aggressive delivery SLAs and their consumers have come not to expect it. This is an extremely hard behavior to undo - and I personally admire them for this.
I am assuming your intent of asking “how do they verify sellers” comes from the FBA experience where Amazon verifies every product that is being shipped. This is a value-added service a %age of Amazon sellers avail. Wish does not HAVE to have it. It’s good to have it. The consumer is not perturbed by the lack of such a verification because the pricing is SO low and the expectation is that the assortment in Wish is going to hard to find at this pricing elsewhere / I have to look really hard.
Verification of sellers is a standard practice and I am sure they do this. Depending on the size of your Ops team, you can have 5-6 people visit factories in China regularly to physically verify sellers. Online verification is also a standard checklist. If Wish was smart, they would probably ask them to add in links of their online stores from other platforms.
Standard practice in China for payments is via escrow. Ensuring delivery of items is a mix of seller ratings (ingrained into their personalization algo), buyer reviews, releasing payments to customers only upon conformation of delivery. Returns are complicated in general, and particularly with cross-border commerce. Happy to chat about it offline!