favoritism because we ate the same ethnicity ???

recently at my job i had a guest attempt to argue with me about knowing how to do my job and argued that i. didnt know the policies of the company i work for. afterward he said that because the fact that we're both mexican i shouldve made an exception for him and shouldve treated him better . I treat everyone the same with respect courtesy and kindness. this shouldve had nothing to do with nationality ir ethnicity at first but once he said that it pissed me off how he thinks. that id favor someone because of thier race ethnicity or color .