Partially true, employees can refuse or resist in other ways, in that case you risk losing out on promotions or even your job and needing to take a lower paying job. But generally I think the cause is that bosses have a lot of power and it’s really easy to pressure employees into working extra.
But that’s not a problem that stems from inequality, it stems from culture.
Are you making an argument or a sermon?
It doesn’t matter if the poor work harder, what is a fact is that the poor work fewer hours and this is a link I just posted.
The fact that the hours increase with income across the board is honestly one of the best ways I can think of to falsify the author’s claim that the high working hours in the US are due to inequality.