Reihan makes an essential point:
France, for example, has higher output per hour but to reiterate: while we could characterize this as an income vs. leisure trade-off, we can also characterize this as a function of rigid labor markets that have led to persistently high youth unemployment rates in Europe. See Annie Lowrey's Foreign Policy article on this subject. Your 10-person firm's productivity would increase if you fired the nine least productive employees, or the three or the one. There is a learning curve, and younger workers tend to be less productive than older workers.