It's kind of like real life. In the earlier analogy it's possible for a person to take some time before they can do their job, maybe because of outside sources. In the same vein, to fully figure out why these people are taking so long, they have to shout out their reasons, therefore taking up a (miniscule magnitude) bit more time to complete their jobs. Similarly, in computers they have the same thing. It's abstract but the deeper they go, the longer the time it takes to complete the job. In essence: loading bars did their job perfectly. They estimate how much time a job can complete, similar to a queue.