You can often avoid asking the "why" question explicitly. If you instead ask about the unintended consequences of the current policy, people will elaborate on the reasons why the situation is undesired, without you asking for it.

For example, in the third question of the article you could ask "Is this the usual level of lubrication?" and you will reach the same conclusion of "No, the oil pump on the robot is circulating less oil than normal."

It can be done without just seeming rude. You just have to practice a bit.

The point is to be the boss, then ask five times.

Indeed!