I’ve read (and participated in) a massive number of TSR’s threads on the TTC, and I do believe yours is one of the more rational discourses on tolls that I’ve seen.
Don't get me wrong -- I wasn't a supporter of the TTC. I think that we could use an upgrade of our existing corridors -- I-35 is getting really crowded, especially between Austin and Dallas. But, I don't see a reason to build a whole new highway.
Sections of I-35E between Hillsboro and Dallas are being rebuilt, but they aren't expanding them to 3 lanes. Maybe all the through traffic is going to Ft. Worth instead, but I don't drive that section.
As I noted in another reply, the banning of trucks from the left lane over an approximately 70-mile section of I-35 through Austin seems to really help the traffic flow. I've also driven the 130(?) bypass around Austin, and I'm not sure it was the right solution -- but at least they made it a toll road, instead of wasting gas tax revenue on it.
However, I'm really happy that they built the extension of MoPac to 45 (and connect to I-35), and I'm more than willing to pay the tolls to use it. I've been driving that section of road several times a year for the past decade, starting back when it was just two lanes. I don't have to do it very often, but the new road takes a half-hour or more off the time it takes me to get out of Austin on a Friday afternoon.
Thanks for the comments.