If WHC were to post their ending TBR auctions prices, I don't see it "helping your sales" unless it's only the really big, high profile ones that go into the thousands of dollars. Going the other way and displaying every single sale likely would have a negative impact on your customer base, and without much promotional value, thereby creating friction.
At the end of the day, a business needs to understand who their customers are and serve them, while also making judicious use of self-promotion techniques.
And yes, these WHC TBR auctions are theoretically "public" but only for a limited time, and we're talking the ability in 5-10-20+ years from now for any domain buyer to easily run a price search on any WHC TBR domain without understanding an iota of how the domain investment business works - STR, commissions, renewals, time investment, hosting, etc.
I am not sure that anyone but a domain buyer would be served by compiling a database of all TBR auction sales.
Compiling the cream of the TBR crop for WHC to help build their customer base? It might be a necessary evil as these tend to get reported anyway.