It’s the height of summer in the southern Chinese city of Guangzhou, and the heat is relentless. The sun beats down on the streets, evaporating the rainwater and creating stifling levels of humidity.

In urban villages -- slums, essentially -- around Haizhu district, where tightly packed buildings block the sunlight, the ground stays wet longer, making the narrow alleys slightly cooler than the main roads.

Inside the buildings, migrant workers from across China labor in garment factories to produce clothing for super-cheap fast-fashion brands, mostly SHEIN, which has been making inroads into American and European markets.

They work 12-hour shifts with minimal rest, yet they are highly skilled in producing whole garments from cutting to finishing.

Everything they need — jobs, housing, food, and essentials — is only a 10-minute electric scooter ride away. Yet their employment is often short-term and informal, and they’re not included in local government welfare or social security systems…

To meet SHEIN’s demand for rapid turnaround times, factories now send fabric pieces to remote processing sites. Vans from Jiangxi or Hunan provinces line the streets, offering daily transport to inland counties where wages are lower.

SHEIN operates a totally digitized supply chain, yet its hiring practices are the same as those of low-cost wholesale garment traders…