This.
Caveat emptor is so old that the language is not even spoken anymore...
Though there were some regulations put in place here and there that were supposed to chip away at the whole "buyer beware" BS.
As products become more complex, leaving the buyer fully responsible for entirely testing something is.....well, silly.
Want to buy a cellphone or a car? Are you prepared or equipped with the millions of dollars of equipment that is necessary to fully test all of its subsystems and components to ensure that the seller is in fact delivering on the specifications? Is your anechoic chamber prepped, with calibrated measuring equipment to ensure that the EMI output of the phone's electronics are within FCC specifications, and that the signal output strength and receiver sensitivity are as-advertised? Are you prepared to x-ray the ICs to try to determine if they are genuine?
Regulation is supposed to be there to hold sellers to their word or face significant legal consequences. Instead, we see protections eroded away or bypassed, as is happening with Amazon and other such "marketplace" locations that go to great effort to make the marketplace aspect appear fairly seamless. "Buyer beware" - if you don't even know that there are certain kinds of problems to look for, how would you even start?
"Google: Please tell me some things about something that I don't know I need to be asking about."
Unknown unknowns.