Amazon helps them do this, by imposing a "most favored nation" clause on its sellers that requires them to sell on Amazon at a price that matches or beats the price charged everywhere else (Target, Walmart, a mom-n-pop, or the factory store):
pluralistic.net/2026/02/25/m...
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Pluralistic: The whole economy pays the Amazon tax (25 Feb 2026) – Pluralistic: Daily links from Cory Doctorow