Again, this would need to be academically researched, peer reviewed and debated.
I'm content to say from the bleachers that there are chickens in the mix, as well as eggs. Maybe we don't try to reduce to a linear cause-effect hypothesis.
The historical take is - the original GO build along the Lakeshore was clearly proposed as an alternative to costlier highway construction, recognizing that urban growth was already happening between Hamilton and Oshawa, and transportation (much of it peak commuting, although all-day 2-way mobility was clearly intended) needed to keep pace. The communities along the line embraced the proposal because they recognized it would support their growth (some of which was happening anyways, but there was opportunity to stoke the fires) and some communities not on the line grumbled, mostly because they were excluded.
The original GO was proposed as a three-year trial, because no one really knew that the concept would prove successful. One old-timer who worked for GO at the beginning told me they were astounded at how quickly ridership developed - within a few months it was obvious the service was justified. That ridership came from communities as-built in 1967 - so arguably GO was both a response to existing demand as well as a stimulus, and not a response, for much development that happened after that date. And that in turn led to those other communities concluding that they absolutely wanted GO also.
More recently, if you follow the remarks of suburban mayors and councillors around the GTA, they all say that GO is mission critical for their communities.
Here's a news clipping from the original GO announcement May 20 1965 - in fact the concept had been clearly expressed back to when the CN bypass was first planned and designed, but the 1965 announcement was the actual commitment decision.
- Paul
1965.... in fact, the idea
- Paul