Ah, the venerable GO train, it services the entire Toronto metropolitan area. Though I lived in this area for 11 years, I seldom took the GO train.
Five years ago I purchased a vehicle online, located in the eastern extent of the Toronto area. Caught a flight into Toronto (TO), hoped on the UP Express which connects the airport to downtown TO and then the GO train to Oshawa where a connecting GO bus distributed the passengers to their local destination. Dropped me within two blocks of my destination.
Cost me about $25 to effortlessly traverse all of Toronto environs. Clean, simple travel, but I doubt it’s efficient since it’s owned and subsidized by the Ontario Govt.