Good thoughts Lucian. If an org has expats doing the same work as locals but paying them more then it seems wrong from both a org and development perspective to let the expats go and hire on locals. Saves money and that situation can be avoided.
In general, companies and orgs should only hire expats when they have to and communicate why those expats are there and why locals are not in those positions. Communication is always important and living standards (cultural) issues are another layer that has to be addressed.
I understand that US/UK orgs and companies don’t always do this but that is both a sign of inefficiency and trouble with leadership.