They're low in Europe too. The first thing I can think of is that American tech companies are generally much bigger than their Canadian and European counterpart

They're low in Europe too. The first thing I can think of is that American tech companies are generally much bigger than their Canadian and European counterparts, and therefore have much larger resources financially to pay competitive salaries. On top of that, the American tech industry has a huge number of both existing companies and new startups entering the picture due to the entrepreneurial culture and VC funding infrastructure. As a result, the job market in the US is more competitive for talent, whereas Canadian applicants have fewer companies to choose from if they don't want to leave the country, and therefore less leverage for salary.