The way I would answer is that when it comes to a municipally imposed tax, they have much more information and much more control to have the tax apply in very specific areas. When you're applying a tax at the federal level, it needs to be applied consistently across Canada. We try to introduce rules that would apply consistently across Canada, based on population statistics.
That was the approach we took to try to get as much consistency and fairness as we could across the various regions, which are quite different from province to province to province.