How are customs fees determined?

Answer 1

Congress establishes the customs duties paid on imported goods. This is to "level the playing field" for companies that produce the same product in the US. Some times there is not a direct relation between the item on which the tax is levied and a product in the US but the goal is the same.

Answer 2

Customs duties are commonly levied to level the playing field between cheap imported goods and more expensive domestic goods. A worker at a factory in China makes about 75¢ an hour vs about $15.00 an hour for an American factory worker. Aside from quality issues, American goods can't compete with those costs.