It might be that historically the diversity of the US is partly responsible; where there is wide social and cultural variation among both employers and employees then the establishment of a consensus about what working conditions are fair and reasonable becomes more difficult. If you've grown up and started your career in an atmosphere of tough working conditions and demanding expectations, then as an employer you're going to have similar expectations of the people you hire. To someone who has grown up in a more collaborative or cooperative situation designed to insulate colleagues from external pressures, the demanding productivity goals of the former context may seem irrational or oppressive. Perhaps there is some correlation with the variety of household income situation experienced growing up - marginal (waged) or fixed (salaried) economic inputs are likely to influence perceptions of appropriate output.