I agree on all accounts, except for the who.
Immigration is a Federal policy, making sure those they allow in adhere to and adjust to Canadian culture and language, is their responsibility.
Sorry, you're right. I was confounding two things there. Here in Ottawa I'd met one woman, born and raised in Quebec, who'd moved to Ottawa with her ex-husband and then of course got a divorce. For reasons I don't know, she chose to remain in Ottawa with much difficulty in her job search owing to her poor English. For immigrants, yes, Immigration Canada can filter out those who don't know the local language (and even then, what happens if an English-speaker moves to central Quebec after becoming an immigrant?).
Somehow though, I doubt the idea of some kind of language card determining where you can travel within Canada will be politically palatable any time soon. For this reason, to ensure we don't end up with French Canadians outside Quebec and English-Canadians in Quebec failing to find work owing to the language barrier, our Ministries of Education need to do a better job of ensuring all Canadians share a common second language at lest. That is an economic imperative, and let's make no mistake of the economic costs of supporting those who cannot function because they don't know both official languages.
Immigration Canada can do very little about Canadians crossing the geographical language barrier within their own country, or native-born Canadians who live abroad for years and then return with a poor mastery of their national language. I'd met a couple cases like that too. Again, since they're born Canadian citizens, there is nothing Immigration Canada can do about them. Granted in that last example, our schools could do nothing either since the person would have been abroad until adulthood. Under such conditions, you'd want our common second language to be an easy one to learn so that such citizens can integrate quickly into the job market at least in the more cosmopolitan parts of the country. As native born citizens, they can't be refused entry back into Canada. Yet i we don't want them on welfare for very long, we need to be sure they can learn some common language quickly. This is where I suppose immigration Canada could take responsibility to integrate native-born Canadians who spend their childhood abroad too through language-learning programmes.