>To make this claim about the US is to overlook that basically all western countries have 40 hour work weeks.
>Are they all failing democracies too?
If said populations voters in general think otherwise and its viable to execute, then yes. If not, then no.
The point has very little to do with 40-hour work weeks and almost everything to do with the lack of policy reflecting reasonably implementable wants and needs of the population at large (again, while not trampling on human rights of minorities).
The reason you see Americans hating on America is because they're unhappy in some way shape or form. Looking at those complaints externally, one might be inclined to dismiss those complaints because the situation is better than other locations relatively speaking in some respect from outside looking in. Ultimately, that doesn't negate the unhappiness of those complaining or a failure of a system designed specifically to address those shared views and frustrations through policy. It's possible for some things to appear "better" from the outside relative to another basis and still be undesirable by the population at large.
I'm not well versed in labor rights in every country but in the US its not great, I can assure you. If you're comparing it to Somalia, it's probably amazing. That doesn't mean it can't be better in the US. Americans are often comparing America to itself and usually in a historic context: are things getting better or worse? We want to see progress, improvement in our lives or at least stability. That's of course not always possible because reality sinks in. When the pandemic hit, it wasn't a situation we could just "policy away" a viral infection without tradeoffs (social distancing, isolation, etc. were policy based but had ramifications on people's lives).
I had a colleague from India who shared this frustration, they came from poverty in their country and moved into a high paying tech position here and would often bring up the same point that while so many complain in the US, "its better than many places." That point isn't invalid but that doesn't dismiss the desire to make it even better here, especially if it's possible and it's not the case of simple power imbalances. I came from poverty in the US. Maybe my poverty wasn't as bad as his poverty as a basis of comparison? Does the comparison really matter? We both want enjoyable happy present and future lives, let's focus on that instead of "who had/has it worse" and not use the worst to set the bar of progress.
So, whether or not the situation is worse somewhere else doesn't invalidate frustration unless you are against progress for a population in general.