Look at what happened recently with transit funding. They agree to pitch in for a couple of transit city lines. Instead of showing any gratitude for the first significant federal involvement in urban transit in this region in a long time, Torontonians immediately fell upon how the funding was insufficient and how they weren't giving Toronto special treatment for its streetcar buy (never mind that Mississauga, Brampton, York region etc. all opposed special treatment for the 416). If you were looking at that as a Conservative, how compelled would you feel to invest anything beyond that little test run? If giving transit dollars actually gets enough complains to make you less popular, would you be willing to simply rain dollars on the city?
What I find striking is not that the Liberals sweep the 416, it's that they do it by such large margins when they really don't do much for the city when they are in power.