The issue is they might run out of normal countries. In developing countries they would quickly become target of local corrupt officials. They would basically suck out whatever they can from companies that would attempt to do billion dollar business there. You can think of them as some mob from mafia movies. There is no way Microsoft would prefer to deal with that kind of folk instead of just hiring American people

Microsoft is located in Bangalore and Hyderabad. Both of those cities are not exactly known for their corruption. If you want corruption, then Delhi is your best bet.

What if the bribes are still cheaper than paying a US citizen? It would still be cheaper than hiring a Us citizen I think