I agree totally that mistakes will happen, and big contracts with higher prices are negotiated when you're in a rush. We all know that. However, with regard to mistakes as to what you're buying and who you're buying it from, there's no way of knowing what's happening except in an audit, years later. Think about two or three years from now. Information as to what went wrong will probably be known, but the people who have already received all the benefits from it have disappeared.
It is not that hard to have checks and balances, but it's systemic systems that have been put into place to protect people from learning the truth early.