That's why he's able to get away with this money grab. People don't think he's going to pull the plug on our "Free" freeways. He's about to.
You haven't seen the latest transportation bill that Congress is about to pass - it starts the process of tolling on the existing interstates.
Also, take a look at this article:
http://www.borderlandnews.com/stories/borderland/20040925-172793.shtml
It talks about putting toll booths up on I-10 near El Paso. While the plan did get rejected, the article makes no mention of the feds preventing the tolling.
There are similar plans in work in Pennsylvania (I-80), and Virginia (I-81), both of which are currently freeways were paid off long ago. These plans are still active, as far as I know.