https://www.vice.com/en_us/article/z3v5j3/us-airports-no-longer-have-to-build-their-own-crappy-trains

On January 12, a time when most of us were distracted by other events pertaining to the federal government, the Federal Aviation Administration updated some rules that will have huge implications for how travelers access airports via public transportation, and even for public transportation systems as a whole. It is also a correction for one of my pet peeves about U.S. public transportation, that we have spent decades building trains-to-the-trains to the airport. This unique type of U.S. transportation has no commonly-recognized name, and I will soon arbitrarily assign a term for them just to make everything easier. 

They do not have a name because they make no sense and have no good reason to exist.  The train itself should just go to the airport, like they do in virtually every other airport with a mass transit connection in the world. These useless trains only exist because of byzantine bureaucratic rule that has condemned U.S. travelers to this crappy extra train for no good reason. And it's finally, finally, finally fixed.