Something may have changed more recently. The first stage of the Eglinton Crosstown LRT line in Toronto looks like it will come in at around (converting currency and distances) 9B for 12 miles. Locals generally don't seem to think this represents a success. (Despite being light rail, about 2/3 of this first stage will run underground.)

(The REM in Montreal - https://www.cdpqinfra.com/en/projects/rem - is doing much better than that, despite going over budget and being delayed quite a bit.)

The Sheppard line is real. It was constructed about 20 years ago. I have used it.

>Because they’re both between Los Angeles and San Francisco.

This explains exactly nothing to me. There are many cities between Toronto and Montreal (the two largest CMAs in Canada, and about 88% of that driving distance) and I can't imagine why anyone would regularly travel between those two, either. Nor can I imagine why someone would make regular trips between Belleville and Ottawa (very close to the Bakersfield-Merced distance, and two of the larger cities in between).

>If not trains between cities what do you consider public transit?

Subways, light rail, streetcars and buses, all operating within a city. And, yes, trains operating within a CMA. (GO Transit trains from Toronto can get you as far as Kitchener, but as far as I know it's a vastly less popular route than the main Lakeshore lines. From Hamilton to Oshawa is definitely not solid built-up area, but it's pretty dense.)

I can't understand why this would be non-obvious. Maybe there's a cultural difference. Are Americans really so dedicated to urban sprawl that residents of a metropolis with an 7- or even 8-digit population might still require regular intercity travel to go about their lives?