You are accustomed to being able to buy any random product in any store and be assured of the safety of that product. That is because of a vast array of consumer-protection law that exists to do just that, and has control over the retail "walk into a bricks-and-mortar store" supply chain. There have always been ways to circumvent this, by working with smugglers with shady little shops, flea markets, etc. The smugglers take advantage of the fact that Customs has bigger fish to fry than looking for look-alike Wagos that aren't UL Listed. But this was only a problem for people who actively sought out shady dealers.
Then what happened? eBay brought smuggling to an industrial scale. Then Amazon figured out they could set up a warehouse, declare it a Free Trade Zone under NAFTA and since some products might direct-ship to Mexico, Canada, Bermuda etc., US customs could not enforce US law on the contents of the Free Trade Zone.
But of course Amazon would be liable if they sold the item to an American address. But not if the seller was actually a 3rd party and Amazon was only a drop-shipper. So that's what they did - Amazon Fulfillment drop-ships anything for any 3rd party (many eBay seller use it in fact)... and Amazon also allows 3rd party listings on Amazon's website, so Amazon is eBay now LOL.
They then make the listings as difficult as possible to distinguish from Amazon's own product, for which they are responsible. They've really got it figured out.
So your intuition is "something protects our product stream from dangerous junk" doesn't work on mail order goods.
Your seller of Chinese carpola would be happy if their product works for you, but they don't give a darn if it fails. They have no liability whatsoever if it fails. Insurance companies have tried and tried to sue them, but they're behind the Red Curtain and untouchable. Don't you notice that the seller names are obviously "made up" like KEMTOO" or the like? I have names for them - there's IkeaGuy whose shell companies sound like Ikea items, and All Caps Guy whose shell companies are random letters in all caps. Do your grandparents remember the halcyon days when the KRLWOMP jingle was heard on radio? No.