Consider California. It's a one-party state. One party has the governor, lieutenant governor, 30 out of 40 state senators, 60 out of 80 state assemblymen, both senators and 43 of 52 congressmen.
They're all more or less aligned on their vision. And their vision sounds great. High speed rail or low cost housing for instance. Nothing prevents them from capturing their vision, and yet they fail.
Better video explaining the delays: https://youtu.be/2NK0wBBZZ24
Anyone (video producer included) who doesn't account for this when talking about cost changes has an agenda.