I've seen a lot of complaints about the caps (wasn't sure if they were widespread or not). What keeps the caps in place if they're universally disliked? I've always thought of Canada as a fairly responsive democracy.
Nope. We elect one group of corrupt assholes to run things, and then complain about them being corrupt assholes. We keep re-electing them till they do something so hugely scandalous that we elect the other group of corrupt assholes instead. And then keep re-electing them until they fuck up so badly that we switch back to electing the first group of corrupt assholes again. Our government is currently pushing for more restrictive drug laws, including for weed. They are pushing for mandatory minimum sentences for non violent crimes, and for privatized prisons. These things are almost universally opposed by Canadians. It simply doesn't matter, we re-elect them anyways.
WTF!?! Is it that US is trying out National Healthcare, so now Canada is going to try out some of the worst American ideas? I don't know much about Canadian politics, but the things you listed are some of the worst policies United States ever implemented. Why on earth is Canada trying those things, I can assure you, private prisons and mandatory minimum sentences are NOT working here in US.