Not living in the USA, but I have never heard of the idea of a city drawing transportation lines to an empty area in anticipation of new buildings. Transportation is always reactive in my experience, especially if we're talking about costly things like metro lines or trams. You can't predict what will attract people to some area, so building a line to nowhere and expecting developers to move there because an unused line now exists is a waste of public money.
The reason places like Tokyo, Hong Kong and Singapore have such great public transport is precisely because the rail planners work hand in hand with urban planners. Railway construction is largely financed by property sales (both residential and commercial) and when done well is hugely profitable, as the former richest man in the world, Yoshiaki Tsutsumi of the Seibu Corporation, can attest.
Retroactively building a subway line in an already densely populated area is a hugely expensive exercise, as most recently demonstrated in NYC itself with the 2nd Ave extension.
I think this is pretty commonly known, but the railroads built the US American West. It was a hugely speculative endeavor where railroad companies would buy up worthless land for cheap, hire unfavored immigrants and work them harder than anyone else would work, and then recoup costs by selling the land of the railroad towns.
The ongoing transit expansions in Stockholm were green-lit on condition that the municipalities getting increased transit access would invest in building housing in the vicinity of that transit.
You can definitely predict what will attract people to an area - rapid access to everything that the downtowns of cities provide is one such thing.
My wife and I were going to a graduation party in Maryland and figured we’d stay in a hotel near the end of the metro line and ride into DC to see the National Mall, Union Square, etc.
The Shady Grove end of the red line has a large development of mixed commercial and residential of buildings that are uniformly about 5 stories (I think) tall that was built to go with the transit line, I understand it is like that in Virginia too.
China is famous for building metros before building the rest of the city.
Land near public transport services is generally prime real estate. The only developers who wouldn't jump on this opportunity are the ones that hate money.
At a certain point in time, building new streetcar lines and "streetcar suburbs" along those lines was fairly common in US cities. Often the property developer and the streetcar operator were the same company or ownership:
Most of those have since had the streetcar lines removed or abandoned as cheap cars and gas replaced them, and the incentive for the original developer to maintain them went away.
The lower mainland (just outside Vancouver) has the Millenium Line extension. It was, when planned and built, called a train to nowhere. It doesn't go to nowhere anymore :)
