This is literally the point of customs. Otherwise, literally any product regulation would be toothless as foreign companies would simply sell us products that meet the requirements of their country, not the US. Since that does not happen at scale, it would seem that US customs does have some ability to enforce US regulations on foreign sellers.
If I were to say, purchase 100,000 gpu's direct from a chinese manufacturer, and half of them were dead on arrival, what is my recourse? Where does customs fit into that recourse?
Now if I were to purchase them from an american company, I may have an opportunity to sue.
You could sue the Chinese-owned American shell company that imported the GPUs. I’m sure they didn’t wire the money away and close up shop immediately, like plenty of Amazon importers caught selling counterfeit or downright dangerous electronics.