It's not that easy. There are tons of examples where driving to work makes much more sense.
I live in Cabbagetown and work in Markham. My drive home today in the rain took 35 minutes door to door. Average commute is about the same both ways every day unless there's a blizzard (those are the work from home days). I used to work at Yonge and Lawrence and took the TTC everyday and the commute took as long or longer once you include the waiting for the never to arrive or overcrowded streetcars.
I'm not against promoting walkable, dense cities, I wouldn't live and own in Cabbagetown otherwise, but I do not think European cities built upon medieval origins reflect the realities of North American cities built around sprawl and car culture. If we don't like the sprawl and car culture, then you need to promote employers to stay in the city, and you need sufficient housing to give the employees somewhere to live, but we have some of the highest corporate property taxes in the GTA (my employer in Markham intentionally moved their office and plant from Markham and Sheppard to save significanty on property taxes). Furthermore, the city seems intent on building condos on top of all its commercial land, promoting the de-industrialization of Toronto instead of providing incentives for those lands to be used for employment growth. The factories that used to reside on those lands are still in the GTA, they haven't all moved production to China, but instead they're in Markham, Mississauga, Vaughan, etc.
Meanwhile the city seems intent on erasing their competitive advantage in residential property taxes, and in turn erasing the incentive to keep your employees in the city, by increasing taxes, and enacting more fees such as vehicle taxes and property transfer taxes. Also, the city does nothing to promote the building of market value rental housing stock for families (as opposed to one bedroom condos), thus pushing the city's potential employee pool further away.
If you want an urban city, you need to keep your workers and their employers in the city, and you do that by providing financial incentives. Vaughan, Markham, Mississauga, etc are all working hard to attract Toronto's employers away. In turn these outlining cities will take the employees away too. What is Toronto's plan to stop them?