These things are typically boondoggles for the airport authority, the landowner who sells it the land, and the construction companies that inevitably run many years and many millions of dollars over budget.

The customers wind up paying for it all through hefty facility and transportation fees which will no doubt shortly be added to all DEN rentals, years before the facility ever opens. Some of the facilities do wind up being an improvement over the prior set-up (e.g., SFO), some not so much (e.g., SAN).