Even if the pay by salary amount is fair, these workers can be exploited to work more hours than their non-H1B colleagues such that if their pay was broken down hourly it would be comparatively lower.
Back in their home country they are probably expected to work those same hours (or more!) for a lot less money. By our standards it is exploit, but often for them it is better.
I understand their incentives. But the fact that they are exploited here, just less so still, makes the exploitation wrong. The H1B program needs to end.