I'll completely agree that the analogy is imperfect. Yet it only has to stretch this far: it's just as bad an idea for a mall to literally vet every item sold

I'll completely agree that the analogy is imperfect. Yet it only has to stretch this far: it's just as bad an idea for a mall to literally vet every item sold by its retail occupants as it would be for Amazon. In fact, no retailer does this. Consider any direct seller of a wide assortment of retail goods, e.g. Home Depot, Walmart, etc. None of these have rigorously "vetted" every item that comes through their doors. They certainly get problematic goods, and deal with that after-the-fact two ways: to purchasers via customer returns and support policies, and to suppliers via feedback into their supplier relationships (give us bad stuff, our $$ go elsewhere; contracts; etc.). The idea that a retailer should be held a priori accountable for third-party goods it sells smacks of the same kind of thinking that suggests ISPs should be held accountable for third-party content flowing across their networks.