The expectations are absolutely communicated, but usually behind a closed door, between the CEO and a consultancy's senior partner that may not even be involved

The expectations are absolutely communicated, but usually behind a closed door, between the CEO and a consultancy's senior partner that may not even be involved with the project directly (because he's too high up). And there's no paper trail behind it (the CEO wouldn't want to be blackmailed later), but the agreement is upheld, because consultancy knows that if they don't deliver, there will be no further contracts coming in from that CEO.