I didn't even realize this! I never really minded the speed with Go, just the frequency (especially when you tap as the train is leaving) and that if you're going 1 burb to another well you're probably going to take a bus that doesn't come that often, and have to wait in the sun/cold for it.I once showed the average driving time during peak hours on 401 from western edge of Toronto (Mississauga border) to the eastern edge of Toronto (Pickering border). Average speed during rush hour was better than average speed of Lakeshore West line from Clarkson to Union (this also happens to the fastest GO line). Of course the difference increases even more outside of rush hours. TTC is even slower than GO. If you have to change vehicles, that takes additional time, something that you don't have to worry about while driving.
For transit to be competitive, it needs to be faster and safer (or at least perceived to be safer).
I see people getting yelled at so frequently on TTC that I have stopped using it. I hate driving downtown but I do that now on weekends when my GO line does not run.
Go is also terrible when they have a closure or suspension, it's like figure it out on your own for a lot of the stops!