Does anyone know anything about this? (I edited this so that whoever traveling to Orange County may find this useful) I received a letter from thetollroads.com asking for $6.25 fee. And it warned me that if I wouldn't pay for it, I would have to pay $100 more after the deadline. Why would a non-government company in Orange County charge me? Is that a scam?
When you entered one of the roads, you would have passed under an electronic sensor which reads FasTrak transponders from those who have them, and takes license plate pictures in order to bill those who do not. You also passed under such a sensor when you departed the toll road, and a sign which advised you to visit thetollroads.com within five days to pay the toll.
If you plan to drive that way again, you may wish to obtain a FasTrak (which is good for most California toll roads and bridges), or sign up for an ExpressAccount, which bills tolls to your credit card each day you drive, or on a prepaid basis, but only works for The Toll Roads. They're currently offering a $10 in free tolls promotion for signing up, which would cover your recent trip. Given where you live, though, you may find Metro ExpressLanes (a FasTrak compatible system) more advantageous...