I think the suprise is the implication that the bus goes from CentrePort directly to the terminals. It does not. One boards the bus at CentrePort/DFW TRE Station, rides for 10 minutes to REMOTE SOUTH parking area and then transfers to the shuttle that takes them to the correct terminal. One goes to Terminals A & C, one goes to Terminals B & E, and one goes to Terminal D. Depending on the terminal, the internal airport shuttle can add 20 minutes to the ride, NOT INCLUDING waiting times at REMOTE SOUTH.
Oh - if the suprise is referring to ridership, that's no suprise. They've been running better than 2 million passengers per year (6500 persons per day) since service began to Ft Worth in 2002.
I think the suprise is the DROP in ridership in FY2010 of 2.5 Mil vs 2.7 Mil the previous two years.