[alxlaz]

> since most likely the only person with a real understanding of exactly why something is difficult is the person doing the work.

This is often the case in other engineering projects as well.

But there's often less of an incentive to "confirm" that this is the case because if you (claim to) have hired the best people, to have given them the best possible training and working conditions, and every support in doing their job, it rarely makes any sense to go to them and figure out if they're really late because the problem is hard, or because they're just slacking off.

The investigation itself is rarely meaningful. Even if they are slacking off, what exactly do you expect they'll say? Yeah boss, we're just slacking off?

Managers who second-guess perfectly competent teams this way are usually shown the door (if they ever made it to managing something).