The attitude in Quebec is that English is a second language, but it is best to speak French. If you want good service, you have to speak French.
Let me give you an example, which may be a little extreme. I was in a courtroom in a courthouse. My opponent, the judge and I were all anglophones. There was no client, it was only a plea on a point of law. Everyone spoke French. Increasingly, the language of Shakespeare no longer works in Quebec.
Is it a matter of courtesy for the majority? Is it the fear that, if I speak English, no one will listen to me, give me better service or something along those lines? It's hard to say.
The “conventional wisdom”
dictates that if you really want something, such as good service, you have to speak French.