Lately I've grown quite frustrated with people using the term "subway" as a synonym for "underground" rather than the more common and accepted "HRT".
Not once in my life, in any city where I've spent a lot of time, London, New York, Seoul, Toronto, Vancouver, Montreal, etc., have I ever heard anyone say "Meet me at the HRT station". It might be technical; but it ain't common!
If you want to have technical papers, call it what you want. But if the media starts telling people that they are building a streetcar under Eglinton instead of subway, it's misleading.
Remember the fuss when the Toronto Star talked about LRT being built down Spadina, and pictures started to appear of SRT trains running down the median of Spadina? It might have been technically correct, but it set back the project, and confused the public.
If it looks like a duck, quacks like a duck, and swims like a duck, it is a duck. I don't really care if the scientific community concludes that it genetically not a duck; it's a duck! Do you know anyone who goes up to a grebe, and says "Oh look, it's a grebe". Well, there's probably a couple ... but it's a duck!
If we called the tunnel on King Street under the railway tracks a subway 100 years ago, and we called the proposed streetcar tunnel under Queen 60 years ago a subway, then we can call an HRT-sized tunnel under Eglinton a subway.
Besides, if you were going to do it properly, we'd call them tubes or undergrounds.