Typically, subway stations are two kms apart from each other. So unless a patron lives within 1km of a station, he or she is likely to get there either by car or by bus. If he gets to the subway station by car, he’s (and the subway plan is) not helping to ease traffic. And furthermore, he’s going to need a place to park his vehicle at a price. Currently the parking lots along the Sheppard subway line are closed to subway patrons during rush hour – makes sense, huh?
Secondly, if he takes the bus to the station, he’s going by a surface route which is what the Transit City already is.
Bus and streetcar stops are typically at every street block or two. These surface services are much more accessible to a lot of patrons than subway stations. A bus would take the patron to the subway station, but the streetcar would take the patron to his destination. And because of their ease of accessibility, patrons can easily visit businesses along the way. And because of their ease of accessibility, most patrons won’t need to drive to the streetcar stop. A streetcar carrying 100 riders can represent 100 cars off the road. That's one streetcar waiting at a traffic light instead of 50 to 100 additional automobiles doing the same thing.
Replacing Transit City with subways is not a km-by-km comparison. Subways cost 3x more than the Transit City plan. Building a subway would in fact reduce the geographic area of service and thus reduce the impact it would have on mitigating traffic congestion simply because its routes would be 1/3 that of the planned Transit City routes. Imagine replacing 50kms of service for 17kms.
And of course there's the wasted money for work already done and the impending penalties. Not a good start for a Mayor who is supposed to be a penny pincher.