There is also a safety concern with overly cheap tools.

For an example, the adjustable wrench in this article. What happens when you apply a lot of force on a stubborn nut? If the wrench experiences rapid unscheduled disassembly, you now have broken pieces flying in random directions.

In the US, the thing that most prevents this from being a problem is the threat of liability lawsuits. That doesn't apply to a tool made by a small company in China and sold by a fly-by-night outfit on Amazon's marketplace. I'm guessing Amazon is unknowingly the liable party here, but I'm not a lawyer.