While Metrolinx is definitely too secretive, especially when it comes to imminent service changes, this is the one case where I think that secrecy is warranted. Revealing details of their plans to the public is sort of like making promises, which could undermine their negotiations with private parties like CN and land owners which could result in rail projects costing more than they already do.
I'm going to argue here that the promise is already public.........15 minute, 2-way, all-day service on the central portions of each corridor (excepting Richmond Hill/Bala) has been out in the open since the mid 2010s at very least, and is being pushed, openly by the current government in unending ads I see on social media.
The long-haul (outer terminal points) of most of the same corridors is promised as hourly or better.
There's no secret, CN/CP know exactly what's been promised.
The only things not public are the schedule and the price.
Though, arguably Wynne did post a schedule suggesting the majority of improvements would be in place by 2024-2025.
I'm fine with some private discussion for a few weeks/months while Mx/The province haggle with CN/CP on the details, but thereafter, certainly within a year or two of the initial promises, those deals need to be wrapped up and done.,
At which point they need to be public.
Once the government knows what it needs in terms of expropriation, it can move to buy that land before or at the same time as any public announcement. It can also ensure that the price of the land doesn't inflate by using MZO authorities to freeze the zoning of the sites in question pending acquisition.
But west of Georgetown or east of Bramalea they already own the line so this argument does not apply there.
Mx/GO owns the vast majority of their rail, so as a general principle I'm going to say they have little excuse on openness and transparency.