The fact that language regimes differ from province to province reflects the history of each province and the legislative policy decisions they've made within the limits of their areas of jurisdiction. This diversity is actually one of the foreseeable consequences of our federal system. It's normal for there to be differences from province to province.
I would point out that the Parliament of Canada, acting in a federative capacity, can establish a degree of harmony or uniformity among visions of that constitutional bilingualism. Even though provincial legislative choices vary, I think the fact that the federal government and provinces make different choices has more upside than downside.