Whether motivated by outright prejudice or simple discriminatory disinterest, ...
This sentence-piece is taken from a text written on the illegalization of cannabis, stating that Mexican immigration was the reason cannabis was illegalized in the United States.
Given how discriminatory disinterest is being contrasted to outright prejudice, it would seem that discriminatory disinterest is a kind of discrimination not driven by emotional imperatives (like xenophobia, ideology, racism, etc.), but rather other motivations that simply happen to involve racial discrimination (if e.g. discriminating against Mexicans would somehow be economically favorable).
However, I don't quite see how discriminatory disinterest means that. Does the disinterest perhaps refer to the lack of actual interest in the actual race/ethnicity at hand?
Here's a link to the text it was taken from. You can find the sentence in the first paragraph of chapter 1: Rationale in the West: Class Legislation