is not technical culture, but business.

The two current and still failing approaches are.
Limit resources (do what you can with X resources), expectation is set before implementation, so we always under-deliver as far as the client is concerned.

Or
Do everything, meet 'all' expectation and blow the reource limit out of the airlock and call that a failure.

Every approach to agile I've seen assumes that neither of these approaches will have been chosen. Like many assumptions in our game...