Pay people a reasonable wage to live their lives and provide for their families. Just because someone lives in another country does not give a person the moral authority to pay them an amount that does not allow them to properly feed and care for themselves and their family.
It's pretty common to see articles about people moving from SF to the Mid-West, taking a pay cut but being happy because they improve their standard of living.
We also see articles about people moving from the mid-Est to Thailand, taking a pay cut but being happy because they improve their standard of living.
Going by the BigMac index for example, it is perfectly reasonable to think that developers in the Philippines, Vietnam or India would be happy on roughly 50% of a US salary (presumably a non-SF salary too). Obviously this is very much a rough guide, but it's something to start from.
This is a false comparison because there's a third option, which is doing nothing. Doing nothing is worse than causing any size of improvement, and almost all of us are doing nothing. If we are to accept that paying Filipino workers slightly more than the local economy is offering is wrong, then we must also accept that not paying them anything is wrong, in which case we should be going after the hordes of people who aren't doing anything instead of the people who are only doing a tiny little bit.
Nothing could really be more damaging to the development of poorer countries than condemning them to subsistence incomes because we've decided it's only ethical for businesses to employ their workers if they're productive enough after all other hurdles are considered to earn Western wages.