Most of Canada has the same planning problems as the US. Namely, car-dependency. Toronto and Montreal are exceptions, but most of the country follows the same development pattern as the us.
But I think you're thinking about this wrong. Sprawl and transport policy are intimately related. If we do car-dependent development, you get a development pattern that requires cars. Then of course you look at the population distribution and say, it's hard to serve this with trains. But if you started with trains, the development pattern would mirror the transit, and you'd say, wow, trains really solved the problem.
America unfortunately went down the car path and faces a painful correction back to sanity. As we move towards transit and factor in car-driving externalities into the cost of driving, communities that can t feasibly be serviced with rail will die out, as is natural.
But that doesn't mean small villages won't exist. They will just be forced to exist where it is reasonable, instead of in unsustainable locations as they do today.
Why don't rural Canadian indigenous villages have rail service, since Canada and other non-US countries love the general welfare so much?