[1] http://www.reuters.com/article/us-usa-tax-burgerking-idUSKBN...
Canada also has the same language, can have the same time zone as any US location, is closer (no overseas flights) and has established trade relationships with the US.
The issue with Canada is that it's pretty small, population wise. I guess that for those big American companies is simpler to bring the -relatively- small number of Canadians to the US.
[1] http://www.numbeo.com/cost-of-living/rankings.jsp [2] http://www.numbeo.com/cost-of-living/comparison.jsp
Changing the topic... I'm not so sure if Southern Europe is cheaper than Shanghai. The two main cities of Spain rank higher in cost of living than Shanghai, according your link. I guess that defining the "cost of living" is a really complicated problem.
[1]: https://www.glassdoor.com/Salaries/shanghai-software-enginee... [2]: https://www.glassdoor.com/Salaries/vancouver-software-develo...