When talking about the greenbelt you have to consider that the surrounding municipalities fought it leading the NCC to outright buy all the land instead of doing it through zoning. This reduced the scope. The NCC is not a munciaplaity and the Feds have no jurisdiction except for purchasing and being landowners.
Then Nepean and other townships immediately started developing right alongside the boundaries. These townships had just lost a lot of land to annexation with Ottawa and what is a town without development? Nothing. An organization will do what makes them more relevant first and foremost, which for a township is to develop.
I also contest the notion that the greenbelt is a failure if development jumps it or that the planners somehow didn't foresee this eventuality.
Are we better with it? YES by miles. It has allowed us more control in our development, provided greenspace and federal institutional space, and fostered the suburbs into being more of their own cities.
Anyone thinking that development could have stayed within the greenbelt is ludicrous. FFS Barrie is satellite city to Toronto and is an hour away. Better toll the 400 instead of widening it to a
10-lane superhighway.
The options are: continuous sprawl or controlled sprawl.
It is not binary success or failure but a balance of better or worse.