Earlier quoted context omitted.
Retail is so low-margin that it will never be very good. Amazon, Walmart, Ebay, are all very imperfect businesses. Even Costco is rough to deal with for the suppliers - there’s just no way to do this at scale while being all nice and fuzzy Amazon is especially bad though
All they have to do is get rid of the 3rd party storefront and hire people to stock and procure vetted goods instead of having it be a free-for-all.
Think about it - Amazon gets to take a fee on - accepting inventory into warehouse, holding inventory, listing fees, listing ads, sales fee, shipping products, accepting returns, destroying returned merchandise.. and probably a few more things.
Amazon makes money whether the underlying sale of products is unprofitable .. because that's someone else's problem.