The problem with this thought process is the same reason systemic racism is often brought up (Which I don’t entirely agree with, but there is probably an element of truth to it). Most people are not going to openly admit to being discriminatory. And they might not even be self aware enough to realize they are being discriminatory. So it’s not even a thing of explicit bias but your coworkers could be making decisions subconsciously because they perceive a caste a certain way.