Salaried positions are a fuzzy area in this. Many companies seem to feel that if they pay you a salary, they're entitled to your productivity 168 hours per week, and any time that you spend eating, sleeping, having sex, enjoying time with your friends and family, etc. is simply their magnanimous gift to you and your "work-life balance".
This is precisely why I clock in and out, even when not required. And I generally have some sort of understanding in writing that the company's right to my productivity are limited to what I do during work hours on company equipment.