for countries that pay a worker $15 dollars a day put a tariff on the goods produced by that work to total $4
therefore someone importing goods produced by one worker in one day from the lower wage country would spend $20 for the goods from the lower wage country but only $19 for the goods for the higher wage country giving a competitive advantage for higher wages
obviously that is a simplistic example but that's what i mean using tariffs to incentivize better behavior and level the playing field so the most exploitation doesn't make the most money