In the same town I have seen programmers doing similar work can have an 2x or 3x difference in pay. I’ve even seen some working w/o health insurance (turned down a job offer years ago over that) although the AHA helps with that.

Also the offshore devs are at a disadvantage because of distance, different time zones, language familiarity (not only for client comms but to read the docs), cultural familiarity, agency problems, etc. (I don’t like working for an outsourcer if it means I can’t tell the client the truth about why the project is late - the truth might be less bad than what the client imagines but it still could be bad for the relationship.)

The south Asian miracle comes from liberal application of management, more people, lots of documentation - it can work wonders but doesn’t always and adds overhead.