Canada is a developed market, with ready access to US internet resources. Russia a decade or so did not have a market that was appealing from a tactical point of view to Western companies (ie. lack of access, lack of customer $, lack of legal framework, etc).

Now Russia is a more relevant market, but the home-grown competitors are already embedded. Canadians may be miffed at Google.ca's lack of caring about Canada, but they still use Google.ca, and will use voice when Google lights the service up.

(I use Russia and Google here as illustrative examples)