And the Canadians get health care for that money.
That said I've done the cost of living numbers between here (NYC) vs. Vancouver, Toronto, and Montreal, and even with the insane rent here I'm still coming out ahead - way ahead. The salary difference is truly mind-boggling.
More than the salary difference, the kind of work you're doing as a $200K engineer in SV/SF/NYC is very different than the kind of work you're doing as a $70K engineer in Toronto. There is a conspicuous lack of this level of work in Canada overall.
http://www.cra-arc.gc.ca/tx/ndvdls/fq/txrts-eng.html
http://www.investopedia.com/financial-edge/0411/do-canadians...
That being said, with the recent tax increases in the US and the lower of provincial income taxes in many Canadian provinces (I'm looking at you BC), the difference isn't as great as one would think.