Comment by StealthyStart

This is the real cause. At the enterprise level, trust outweighs cost. My company hires agencies and consultants who provide the same advice as our internal team; this is not to imply that our internal team is incorrect; rather, there is credibility that if something goes wrong, the decision consequences can be shifted, and there is a reason why companies continue to hire the same four consulting firms. It's trust, whether it's real or perceived.