They are not RTD. They are Homeland Security.
Although RTD has a right to see your ticket, no one has a right to just demand a photo ID without probable cause. My recommendation to anyone who is asked to do so is: ask the cop for HIS (or her) photo ID. Tell the cop that he is conducting a warrantless search, which is unconstitutional.
We must begin standing up to the police state and not submit to the loss and abrogation of our constitutional rights like sheep.
There are instances where I am not going to argue about the warrantless search, such as before getting on an airplane, or, probably, going into a court. Anywhere else, I am.
***The latest (Sept. 23, 2011): FEMA and Homeland Security have been conducting drills to bus students and teachers to Mile High Stadium for "processing." Given that Denver was the site of the Columbine school massacre--which must have been government-sponsored, given the FBI and CIA agents standing around "observing" while the killing was going on inside; the involvement, according to many witnesses, of many other shooters; and the complete non-investigation and cover-up which followed, involving slimeball Ken Salazar--and the imminent economic collapse, we are on the verge of seeing mass slaughter of citizens by rogue elements in our own government. Denver is a hub.
"Drills," my ass.