I'll explain this shit. We gained independence in stages because we love bureaucracy and didn't do it all in one go
In 1867 the Dominion of Canada was created. Onwards from that point we had control over all internal affairs. We could do whatever the fuck we wanted here, but were still part of the British Empire and were obliged to help them in the event of war (Although we didn't always comply). We were a country, but we didn't have our own international representation. We were a sub country. We just fell under Britain and did so until the end of WWI.
WWI gave a huge boost to Canadian nationalism and desire for a identity independent of Britain. So in 1934 The Statute of Westminster was created which gave Canada, Australia, New Zealand, etc.. total control over their foreign affairs effectively making them completely independent of Britain. This basically killed the British Empire. There was one oversight though. Constitution. We made our own charters of rights and shit, but we could not make any changes to our constitution without going to British courts. It wasn't a big issue, but it was still dumb nonetheless. So in 1982 that's what happened. We were like "okay Britbongs, we made a new constitution, and we made it so we don't have to bother you with it anymore" and then the Queen came over and signed it.
The fucking end.
It was just politics. Shit takes forever to get done if it's not a burning issue. We could have did it back in the 30's or 40's, but we just didn't bother.
