Why employers (in the knowledge business at least) track people by the hour is beyond my understanding.
Because in some countries it is a legal requirement. Where I work, in Austria, there is currently a legal limit of 10 working hours per day and a total of 50 hours per week, except in exceptional circumstances. Therefore, all employees must log their working hours.
I found the process odd when I first moved here. However, over time I have come to appreciate the advantages. I have absolutely no pressure from my employer to work excessive overtime and there is no default culture of long working hours. After 14:00 on Fridays, every week, the office is 90% empty.
I hope this small example helps you to understand why employers in some locations have to track people by the hour.
At least in Germany, working unions are fighting against not counting working hours, because it is better for the employees and is also a saftey net against related health issues. Without counting, legal rules are not enforceable and people may even work on weekends without any compensation. This also leads to the fact that managers start to expect those extra hours from everyone, and consequently see it as an lack of motivation or dedication not doing them.
Attorneys do the same thing. It’s no big deal.