The problem here is that "trusted" is not intrinsic to the character of some third-party. I might trust someone with $100, but does that mean I would trust them with $1,000,000?

The better solution is to not to rely on trust or semi-trust (i.e. trust multiple parties not to collude) at all. Instead, incentivize people to act in their own self-interest (the same game-theoretic assumption underlying the blockchain). This is how TruthCoin incentivizes voters to adjudicate decisions (voters are analogous to miners): https://github.com/psztorc/Truthcoin