That's in an academically perfect economic system, and labor is not that. People have been able to get cheap engineering labor from India for decades and wages have still been climbing. Businesses choose who they hire for a variety of reasons and price is only a single factor.
Additionally, labor has a say in what they're paid as well and knowledge of what the average pay is for a given job in their country, region, or city. They can also talk to their fellow employees when they're hired and then push for a hire wage when they find out they're making less then everyone else doing the same job. Just because someone lives in Wisconsin doesn't mean they just accept any offer at a discount simply because HR has a bar chart says they should be paid 35% less then someone else.
Additionally, labor has a say in what they're paid as well and knowledge of what the average pay is for a given job in their country, region, or city. They can also talk to their fellow employees when they're hired and then push for a hire wage when they find out they're making less then everyone else doing the same job. Just because someone lives in Wisconsin doesn't mean they just accept any offer at a discount simply because HR has a bar chart says they should be paid 35% less then someone else.