Well that's on Amazon then. They could go the Walmart route and enforce in-house random testing on the stuff they sell. Walmart, for all the rightful hate they get, Aldi, Lidl, Costco, Coop, they all have very strict and extensive negotiations for purchase, and they can, do and will refuse shipments from vendors that fail to meet QA.

But they don't, that's how Bezos got one of the richest men in the world. And Amazon got entrenched way too fast for regulators to ever meaningfully catch up.