Earlier quoted context omitted.
Some people prefer working intensely, some people don't. So why demand 8h of presence from everybody as long as the work gets done? From my experience, policies of being in the office for hours significantly reduces productivity, as people spend more time trying to fill their days instead of doing the work. Regardless, it's patronising to effectively treat highly paid professionals like children with dumb, simplistic…
no one works in a vacuum. people need to communicate and collaborate, even when the work is prescriptive. core hours requirements stem from making sure that there are times when everyone can have rich, immediate interactions. not from childish supervision.
In theory, you could have a job where the core hours are just 4 hours a day (most coders do not spend more time having rich interactions), and if you succeed to get your work done, you can leave afterwards.