This is a complicated issue with no easy answers. Contains a discussion of the wage parity issue, along with lots of references. And yes it is about (changes happening to) engineering and lots of other professions.
ILO Decent Work Across Borders Migration Notes. (International Labor Organization)
GATS Mode 4: Movement of Natural Persons and Protection of Migrant Workers' Rights.
By Pradip Bhatnagar.
https://www.ilo.org/wcmsp5/groups/public/---asia/---ro-bangkok/---ilo-manila/documents/publication/wcms_351261.pdf------
Also see
https://www.google.com/search?q="TN/S/W/14" (dispute over whether guest workers should receive wages based on supplying country or consuming country's laws, or no rules at all. (the free market)
Most developing countries argue for the low wages because forcing them to pay wages based on the host country they claim defeats their main advantage low wages.
My worry is, would people in the more expensive countries spend years of time in study to enter technical professions if they knew in advance the pay might be really low, perhaps lower than say a taxi drivers or supermarket checkout person? (professions not subjected to trade-agreement mandated international rulemaking)
Here is another related discussion:
https://library.fes.de/pdf-files/iez/global/06955.pdf--------
Of course all this global capture is not what most people want. So how is this happening?
When we're told anything, which is seldom, we're told by the Davos crowd that its the fault of 'highly mobile global capital's' demands for 'certainty'.