Please think for a moment not only about whether it's feasible for AMZN to run a safety testing program for all possible consumer products of our modern technological civilization, but whether you really want them to be in charge of it. Maybe they should just require certifications of testing in the jurisdictions where those products are sold?
Isn't faking certs already a problem?
Probably. Is it a worse problem than Amazon inspecting themselves would be? Is it a worse problem than Amazon demonstrably already has with policing counterfeits? I'm just saying, you could hardly ask for a less-qualified authority for product testing. At least with independent certs it's vaguely possible to align the incentives correctly. With Amazon the incentives would be hosed from the start.