I have a very US-centric view of the world, even having been to a few other countries in Europe and Asia. But I suspect AliExpress survives because there's a very large part of the world, especially developing countries, that doesn't expect honesty and very much follows a "buyer beware" mindset. Every gone to a market in India? I have. The aggressive tactics, "stretching of the truth", prices (and immediate discounts), and quality are all unbelievably sketchy to westerners. I've not been to China but I imagine it's similar (if not worse) there. AliExpress is a giant bazaar where the merchant in one stall may or may not be there next week. IMO it's up to you to decide if you want to buy from that merchant based on questions you ask, what other customers say about them, whether you think you can haggle a good bargain, etc. There's no FTC or other consumer protection in a giant (online Asian) merchant bazaar, save for whatever your credit card company will do for you.
BTW I suspect if enough people filed complaints with their CC such that chargebacks were astronomical, your CC would jack up merchant fees to cover the risk and/or AliExpress would stop allowing payment by CC because of the losses from chargebacks. It's just that the overall volume for AliExpress is so large that everyone (CC's, Ali*, merchants, etc) accepts the risk and additional losses in order to sell more stuff.
Note that I don't approve of the above, I'm just answer the question of "why does AliExpress not intervene?"
I don't know how AliExpress decides the case but I got a partial refund for my "280Ah" Liitokala cells which clearly had a 271Ah CATL QR code on them and tested at about 260Ah (and at a low C rate... these probably really are even lower Ah capacity technically). I didn't have to provide the kind of graph you did (BTW how did you generate that?) I just did my test, wrote a paragraph explaining what capacity they actually tested at, and asked for a pro-rated refund. The Liitokala store originally offered me $2. I told them these were 20Ah short and demanded they give me a ~8% refund (including shipping and tax). Liitokala did not respond but AliExpress did and within a month I had a $49.xx refund in my credit card.
I do wonder if it's easier to get a partial refund, if repeated issues with similar stores make it easier (or harder) to get a refund, or if it's just all being decided by a call center full of people and each person makes a different judgment call on these refunds.