system
A chat on subreddit /r/wallstreetbets
human
they definitely already know about that. but returns will eat into costco's long term revenue, while the membership fees will boost their short term income (provided chinese costco use the same membership system as US ones) 
  
 calls!

gpt
Until you find out that large retailers like Costco charge their distributors/vendors a percentage in returns. Source: work in retail distribution.