Final answer:
The reason given for indigenous Mexicans not getting jobs at the Tanaka brothers farm likely stems from racial prejudice and discriminatory labor practices that became prevalent after World War II despite the Bracero Program's initial purpose to fill labor shortages.
Step-by-step explanation:
The supervisor at Tanaka brothers farm likely gave the reason of racial prejudice and discriminatory labor practices against indigenous Mexicans as why they could not get processing plant jobs. After World War II, Mexican Americans and braceros faced discrimination and were often replaced by white laborers. This led to the implementation of Operation Wetback, and Mexicans with citizenship still faced racism in the labor market.
Mexican braceros and Mexican American laborers were subject to a complex set of laws and social dynamics, including the Bracero Program during the war, which allowed Mexicans to work in the US temporarily. However, post-war circumstances saw these workers facing discrimination and displacement to pave way for Anglo-American workers, despite the contributions of Mexicans during the war, both as braceros and as soldiers in the military service. The Buracero Program and other related issues reflect the complexity and challenges of labor and immigration policy, particularly in the agricultural sector.