If you buy from an American store, you can file your claims with the store under American law and everything is easy.
If you import from China, American laws apply to you and Chinese laws apply to the seller. If you get scammed or hurt yourself with a dangerous product, you can try two things: sue the Chinese seller in your home country (they won't turn up if the court even cares enough not to dismiss your case) or sue the Chinese seller in China under Chinese law (good luck with that as a foreigner).
You have rights, but your cheap products come at the cost of having to jump through many hoops to enforce them. I don't think many people will follow through on the paperwork required for a Chinese visa just so they can spend months or longer trying to sue a dropshipper in Shenzen, but you could!
As for gross defects and QC: keep in mind that QC on Chinese websites is done to comply with Chinese standards. What's considered carcinogenic or dangerous in one country may be completely fine to sell in another (see: importing American soda to Europe, if it contains any banned food coloring).
Do note that platforms like Craigslist, eBay, and Amazon are often not considered as the business you're doing business with. The same Chinese seller can be active on Aliexpress and Amazon, and you'll still have to go after the Chinese entity if you want your medical bills paid.
Don't buy foreign if you want to be able to enforce your local laws. Buying locally is more expensive, but at least you have an address to sue.