Originally, the National park service ran the tour busses and the state ran the main park. I remember the tour busses going away awhile back after Lady Bird died but since you heard it on the "internet" you might want to check it out first.
I only grew up there but I've been gone 20 years. I still visit my mom and like to visit the park but I never took the tour busses and have never seen any signs.
830/644-2252 - give them a call.