I think there's plenty of evidence in the gtha alone that this works though, the first and biggest example being the GO Train. GO was a response to the massive amount of sprawl Toronto was experiencing at the time, and it was a pilot to an alternative to building new highways. They didn't remove car lanes, they didn't gimp the highway network, they just built an alternative for rush hour commuters, and it was an instant success. They built something that was fast, useful, got the job done, and people came. Something Jonathan English always talks about when he's talking about local bus service is the importance of frequent bus networks. Idk if there's a link for this but in TransitCon he was discussing about the values of frequent bus service even in the most suburban environments. He was talking about how often he's hired as a consultant at major cities that tell them that the outermost suburbs will never have the ridership to justify 5 minute headways on busses, and Toronto proved that this wasn't the case back in the 60s. During that time period, suburbs in areas like Sheppard and Don Mills were first being built as car oriented suburbs, looking extremely similar to areas like Northern Brampton or Woodbridge today, and it looked like the type of suburb which most transit planners would tell you "would never attract enough ridership to justify it", but guess what they did and TTC made a ton of money back then off of these busses. Brampton is experiencing something similar atm. Over the past 10 years they significantly increased the frequencies on Zum, and it went from an underused bus service to over capacity pre-covid, and that's while it was running like 7 minute frequencies, and they did this without removing car lanes or directly gimping drivers. They offered a fast and efficient service, and people came.
If you want some none Toronto examples, look at Washington DC. When it was first proposed and built, many transit experts at the time claimed that the areas that the metro travelled through weren't dense enough to support a metro, and that construction of the metro wasn't worth it and wasn't going to do anything. Shortly after opening it performed way above expecations, and is now the preferred method of transport in the city for Middle and Upper Middle Class workers, and they did so without gimping the existing road network or car infrastructure. The Canada Line in Vancouver... the same thing. People thought it wouldn't do well and that they should build an LRT instead. The reason why the Canada Line only runs 40m long trains and had many corners cut was partially because the people in charge, including the city of Richmond, believed that Richmond was not dense enough to support a metro, and that a light metro was overkill. 10 years later and the Canada Line is at crush point and facing capacity issues without platform extensions and a new set of vehicles, and again, they accomplished this without gimping cars.
So no, time and time again "build it and they will come" has been proven to work and to be an effective strategy.
