No. You have to prove that you are legally in the country in order to apply for a job at these packing plants. By allowing illegal aliens to work in the plants, owners have been able to force them to work extra hours without overtime pay in unsafe conditions with the threat of firing if they complain. Owners have also employed underage workers in unsafe conditions. When one of these illegals is hurt on the job, they are screwed - the company will do nothing and the victim risks deportation if he goes to the police.
The agreemnet is that the workers will be allowed to vote for or against unionizing.
A union will make it near impossible for employers at these plants to continue to hire illegal aliens. It will force them to pay a fair wage and provide safe conditions, disability for workers injured on the job, and probably higher prices to the consumer.
In many cases the illegals who were arrested in these plants were long-time employees with excellent work hitories. BUT both they and the employer were breaking the law.