Many firms in developed countries, countries which have significant worker protections, contract out parts or all of their production to contractors in developing countries, where labor protections are much less. Here is an example.
Made for next to nothing. Worn by you? Elizabeth Paton New York Times February 6, 2019
See full report Tainted Garments. The exploitation of women and girls in India’s home-based garment sector by Siddharth Kara (60 page PDF file)
Image: Old sewing machine of the type used in many Indian homes. Credit Suparna