I think you fundamentally misunderstood the potential issue.
Sure, on a reply based approach you can audit a DNS service.
But that doesn't tell you about other things like "is my DNS provider also providing intelligence agencies with my entire DNS query history?". The issue isn't "oh no the MI6 can redirect my PornHub link to anothe site", but "oh no the MI6 knows every single webpage I visited". Which is a valid worry given the current British political climate.
Sure, on a reply based approach you can audit a DNS service.
But that doesn't tell you about other things like "is my DNS provider also providing intelligence agencies with my entire DNS query history?". The issue isn't "oh no the MI6 can redirect my PornHub link to anothe site", but "oh no the MI6 knows every single webpage I visited". Which is a valid worry given the current British political climate.