Lower taxes, import export tariffs, laws of international business, exemption for shipping from different countries, labor cost differences, financial regulations.
Explanation:
Businesses use many loopholes and rule relaxations to drive up their profits. Lower taxes allow for more investors to find interest and lower import export tariffs make a place a good market.
If the labor is cheap in a different countries the companies ship their product to their and make all the preliminaries for cheap then assemble in the parent country to get a certification.
Companies also use international law loopholes to evade taxes and work around tariffs imposed.