So, to start...Do you know how MUCH it costs to take a loaded class 8 truck across the 407 end to end? For a company without a transponder (and not every carrier uses them as the need is not constant, or they are out of province, or out of country...it's NOT realistic to expect every truck to carry one) and towing a heavy configuration, taking the 407 from Lakeridge road in the east to the 401 exit to the west (what most people would reasonably consider the most common go-around for the "GTA"), it's over $200 after taxes and all the fees. Even if the company has a transponder it's still roughly $150 each way.
So, no, trucks just passing through are not going to use it because they are actually losing money (in a big way) in doing so.
Secondly, a good percentage of the trucks you see in the city through the day are actually doing business IN or around the city, not just passing through.
So, force them to go through at night, you say. Been there, heard that - millions of times, same as all the other ideas by people who have no grasp of the realities of the industry. It would cost the province BILLIONS of dollars in the end - companies would flee the province. It would put many small businesses....out of business, and it would jack up consumer prices (yep, what YOU pay for the stuff on the shelves) because of extra staffing requirements. Because you see, what most people forget is that restricting trucks to only using Toronto roads through the day means that stores that are usually closed at night need to staff overnight to accept those deliveries. And then the companies basically only have a half a work day to do 24 hours worth of work. Try squishing your 8 hour work day into 4 hours and see how well that works for you - same concept.
There are SO many logistical reasons why the "just ban trucks through the day!" common knee-jerk reaction is simply totally and completely unrealistic, but people outside the industry just don't grasp it. If it was so easy, trust me, governments across Canada and the USA would have done it decades ago...but studies quickly show that the reality of this is a financial nightmare for economies, and unrealistic.
And in the end, it wouldn't help anyways - almost all traffic jams are caused by CARS, not trucks - again, spend a day in our shoes and you'd see how traffic jams start - cars will jam on their brakes for the stupidest things - any blinky light even if it's 8 lanes on the other side of the highway, 3 drops of rain on their windshield, a gust of wind, lack of basic navigation ability, and lets not even talk about people who can't merge or exit properly or don't drive in the right lane causing lane changes or backups behind them - THIS is what causes traffic jams. The guys in the big trucks with few exceptions don't do these stupid things - most are paid by the mile and have ZERO incentive or desire to want to slow down not only because slower = less $ per hour, but most are on a schedule as well.
If there was 2 lanes adjacent to the 401 solely for trucks you'd discover that it would be flowing at 100KPH 24/7, even when the 401 is dead stop. Us guys know how to avoid doing the stupid things that create traffic jams.
In other words, the whole idea of restricting trucks to certain hours is not only unrealistic, financially disasterous, but in the end, mostly pointless.