Trade is part of human nature. There are many things and services that people need for survival and convenience that they themselves cannot produce efficiently. Hence, trade between and among people has occurred naturally.
If trade is so basic and important, it should be kept as free as possible, with minimal hindrance and restrictions by politicians and other special interest groups via high tariffs and various non-tariff barriers (NTBs).
For trade between and among people in different countries, or at least within a region to be truly free, trade liberalization should be done unilaterally