The popularity of trade restrictions, tariffs, and quotas often reflects that

The popularity of trade restrictions, tariffs, and quotas often reflects that special interest nature of trade restrictions. A tariff is a tax that must be paid for the import or export of goods. They can be "ad valorem" (to the value), as a percentage of the value of the goods, or "specific" as a determined quantity per unit of weight or volume. Tariffs are used to obtain government revenue or to protect the domestic industry from import competition. Tax or tariff that taxes the products transferred from one country to another. The increase of these tariffs on the products to be imported raise their price and make them less competitive within the market of the country that imports, tending with this to restrict their commercialization.

simpleton is the answer, this is simpleton work