You're missing an important distinction, though: in the US, health benefits are tied to full-time employment, and most places consider anything under 35 to be part-time. I've had several jobs that would force me to clock off if I was at risk of hitting that full-time threshold. I had times where I was struggling to make ends meet, but they wouldn't let me work more. And, at least in my state, if you take on a second job, wages from the second job are taxed at a higher rate.

So 34 American hours and the benefits associated are very different from 35 French hours. Codifying the threshold for full-time employment at 32 hours instead will only benefit white collar workers. Everyone else will just get their hours cut even further and be driven further into poverty.

Basically, we really, really need to fix American healthcare before anything else, because until we're on a single-payer system, most changes to labor law will fuck the most at-risk populations.