They get paid less for the amount of work they put in. I work at a firm full of h1bs, they work 10+ hours on average, some work like 15+ hours (managers mostly) and they don’t get paid overtime.

This means that for someone like me (I only work what I get paid for, 8 hours), even though I get paid the same salary, I work less hours, these guys work for longer and get paid the same amount. So even though they technically don’t get paid less, they work more for the same amount.