The duty for products coming from the US is a lot more than products from UK, Australia and New Zealand. I don't know the exact percentage amount, but if you compare similar Western items in a store like Villa Market, you can see the dramatic price difference. For example, a similar bottle of white wine might be 400 THB for an Australian wine and 700 THB for a US wine. Cheese, canned items, frozen items, is the same large difference. I used to import from Thailand, and the duty incoming from Thailand was 5% to17% on average, depending on product type. I don't know why Thailand doesn't lower the duty on US products so they can import more into Thailand to correct some of the imbalance. Seems simple to me.