Not sure how it is in the US. But here in the UK there's two ways a business can export.

1: They pre-clear the customs duty and include it in the sales total (so it's like paying sales tax at the checkout, except it's the pre-cleared duty fees). Then the parcel has a nice duty paid stamp and goes straight through customs (I guess unless customs are suspicious and check into it).

2: They just charge you the item price with no tax applied. In which case you need to pay local tax and duties applicable once the product arrives. Here it's a bit different. They will hold it at the local depot and you can either go there and pay + collect, or you can pay online and it will be rescheduled for delivery once you pay.

As others have said, it's not a scam. There's no requirement for a business to do option 1, and it's likely only viable for large businesses to register and have someone/software that knows the various duties required for various countries.

I've ordered from newegg and B&M in the past for example, and in both cases the items were pre-cleared and arrived promptly without any hassle.

Maybe there's something similar for imports into the US too?