Why can’t it be defined by daily tasks being accomplished, or the value of the work? If we get our work done early, why do we have to pretend to look busy for the rest of the day? Simple changes in the workplace can set off a butterfly effect of positive outcomes: lowered stress, less traffic on the roads because it essentially eliminates rush hour, less carbon footprint, lower overhead costs and resources, more time for life activities, more time with family, an overall positive outlook on life where work doesn’t consume everything. The c-suite assholes can still get their bonuses. In fact, you would think it drives motivation and productivity levels at work. This is true work flexibility, not the bullshit that companies advertise as a “benefit” on job postings.
TLDR; jobs should be defined by quality of work, not quantity of hours like a robot.
EDIT: I should be more mindful and say that not all jobs are created equal. Many jobs rely on hours worked (such as sales, hourly instead of salary, etc). Maybe I should rephrase it by saying jobs where you find yourself watching the clock scrolling through your phone after hitting your target for the day.