The article talks about more than just working conditions. For instance

While the larger poultry industry in neighboring Arkansas has given rise to worker centers and advocacy groups that push back against unsafe conditions, Oklahoma’s still sizable immigrant workforce has less support

[...]

Immigrant workers are often less inclined than native-born workers to report unsafe working conditions or injuries because they fear losing their jobs or being deported, said Jose Oliva, the campaigns director for the HEAL Food Alliance, a coalition of organizations that represent food industry workers.

[...]

“This industry is really skilled at constantly seeking out who is the most vulnerable or exploitable population, and how do we bring them in,” Stuesse said.