For Singapore, the issue that they need to import large numbers of low-skill / unskilled workers because there aren't enough Singaporeans for those kind of work. Traditional sources of such labour are Bangladesh and India.
Singapore as a financial hub also has large numbers of high paying office jobs. The west is dominant in finance and India Indians are good at placing themselves into these jobs. (Whether they perform well once there is a separate discussion.)
India government has successfully exploited the confluence of these two factors to push Singapore to "balance" the import of both low-skill and highly-paid Indians. Basically, if you want more low skill workers, you must issue more visas for highly paid workers as well.
One way out of using large numbers of low skill workers is automation. That's a long term thing.
