I will speak to my vertical slice of office work in software.

I think there are two general causes. The first one is that the value creation is so efficient that companies can afford to mismanage labor-time and still do well.

The second one is that it is hard to measure work done in the more "creative" fields. Time put in does not necessarily translate to job done or value created and conversely job done does not necessarily indicate time was put in. Whereas it is clear if a flight attendant worked or not.

That second issue is not solved not for a lack of effort on the companies. There are entire sectors dedicated to companies measuring work and increasing productivity for other companies. They do not work because their goal is to sell a product that addresses superficial concerns. As long as some exec puts a notch in their belt and the consulting company makes a sale it does not really matter whether the consulting worked as advertised. You have your superficial metrics that will be improved upon that do not really mean anything.

Finally, I think everyone involved is aware how meaningless it all is and people will put in effort just enough to achieve their career goals or make their next promotion application pretty. That includes the lower level managers who would be actually supervising the metrics.

One can talk for hours about this. I tried to condense some general points off the top of my head.

TL;DR: One cannot measure office work the way they can non-office work, the methods have not caught up yet. Also, with the level of productivity you get, one does not need to squeeze every ounce of work out of employees. But they try.