Every transit agency in the province has this data, down to the boardings at stops. But very few actually publish the amount we want. Generally speaking, they do see it as something that can be used against them. Sometimes they are right; you can make some very critical observations of a transit agency with this in hand.
The few agencies that do post more robust data (monthly ridership, by route, etc.) are generally on the upper end of service quality in the province- the TTC is actually the only one I know of, but GRT, Brampton and Mississauga might as well.
Metrolinx should see themselves as ‘worthy’ of posting said numbers, as their service does not suffer from underfunding that would make them look bad. But, it’s hardly out of character for them to be more secretive than they need to be.
That means we got to wait…. Any day now…. for that damned 2021 TTS!