Would this have anything to do with the bond/deposit put up by the employer/contractor guaranteeing the braceros transportation (to and from place of origin), living expenses and repatriation?
Or that the bracero program was controlled by the independent farmer associations and the "Farm Bureau" and that once their contracts expired, the braceros were required hand over their permits and return to Mexico and that if the employer/contractor didn't provide proof of having paid these expenses, then the employer/contractor wouldn't get their money back?
In other words, the guest worker program worked.