It is a free market isn't it?
What do you mean ? this system is just to make more "protection" and less "scamming" .
You are saying on staff+ can get vouches, it is up to individual members to believe a vouch. Mods have scammed before.
Some people may not want to make their trade public for a number of reasons.
Not being able to rate others unless you trade with them is a horrible idea. If someone whose opinion is not valued by the community is scammed then a scammer will be able to continue to scam and could simply trade with people without reputation.