I was just saying their perspective would "prove it" assuming you and the other person's personal experiences are both valid. But you are making the assumption that it's invalid and your own experience is the only one you can trust as valid. I'm not saying this particularly commenter's experience is hard proof of anything, but it's not hard to find enough perspectives from other people to convince yourself that caste discrimination is likely to be a real problem. The rest of the comment probably bears re-reading on your part. P(N people with perspectives different from your experience are all liars) < P(perspectives different from your experience can be true)

Also writing qed at the end of your comment doesn't make it a rigorous proof, lol. Like, you've already failed to understand the basic concept of sampling bias.