why should anybody's tax dollars pay for any of it?
Good question. I'd certainly be open to ideas there. One issue is that with any transportation line, be it a road, a railway, etc, it's bound to cross many people's paths, thus affecting even those who do not use it. For example, if you build a highway across a neighbourhood, all of a sudden it might hinder pedestrians and cyclists who previously had no highway to cross. From that standpoint, it certainly makes it a community issue to even decide whether or not to build such a line, and how it might affect those whose communities it might cross, with special consideration for those it might affect the most (such as those living right next to the line, etc.).
Now even if we agree to build it, then the question is, who should pay for it. One possibility I suppose would be to make Via Rail pay for it out of its profits, if it wishes to do so. So then not only must the community agree to building it, but Via Rail too. And if it agrees to building it, then how do we pay for it? I suppose making Via pay for it is one option. Alternatively, some kind of resource tax. Or some combination of them? I don't know.