Every single one of those projects is a new road or an expansion. Not a single existing lane will be converted to tolls. So your statement is false, no 'bought and paid for roads' are being 'given' to local authorities to 'covert' to toll roads. Now some planned roads are having their mainlanes built as tollways instead of free lanes, but the reason is to speed up construction. The money wasn't there for completion as free roads, and thus those mainlanes wouldn't have been built in most cases for another 10-20 years. By turning to toll financing many of those projects will be finished in the next 1-5 years.
The toll portion will be the highway that's under construction. The non-toll portion will be the existing frontage road.
But if you think that the state of Texas runs things so well and is still so short of funds that there's no other alternative other than to implement new taxes then by all means, you've reached a space that I haven't obtained yet.