Unless the reviews are submitted in the grad students' names, that sounds like academic misconduct. Can you “anonymously” report this without too much backlash? (I assume the answer is no: you clearly know it's wrong, and haven't done anything about it yet.)
> This is the thin veil that everyone hides behind
There are many places in society where we do this. The thin veil of politeness, lies that everyone knows are lies – like asking "How are you?" without actually caring how the other person is, and answering "Quite well, thank you." when you're neither okay nor thankful.
It makes no sense, but people would behave worse without the illusion. I know not whether the benefits of transparency would outweigh that.