People are paid to be available to do 40 hours a week of work, not to actually do 40 hours of work a week. Sitting around waiting for a meeting to start etc still counts as work because you’re on the companies time not your own.

That’s also where the expectation to go above and beyond comes from. In many office environments actually getting stuff done requires time outside of normal business hours. Paychecks are about hours, promotions are about accomplishing something.