I enjoyed this thoughtful piece Laureli and have experienced some of the same emotions when traveling & living in rural Alaska for the past fifty years.
   That ugly concept  racial & other prejudice - applies to & exists in different degrees in every human. As long as people are obviously different in skin color, languages, height, weight & other aspects - there will be innate prejudice to some degree. Some prejudices are subliminal & not recognized by any but their victims. The "brown" money changers probably had heard of counterfeit money foisted by locals, so you fit the description of local & your money was rejected. 
    It is the duty of government & individuals to referee - to keep the degree of prejudice from exceeding acceptable civil limits. Tolerance must enter the equation to temper innate prejudices & keep them from becoming excessive. 

Perfect absence of racism or prejudice will never be achieved. But we should work toward that as an idealistic goal.