There's another flaw in Dunnam's arguments. Texas is growing economically. It's adding new businesses, new jobs and new residents. Therefore, there will be new taxpayers to pay part of the debt going forward.
Yes, it would be better if there were no debt but the only reason we are having to go into debt to build so many roads is because the money we are sending to Washington is no longer coming back to build new interstates and, after a few decades of pleading to Washington to fund them and unwilling to put it all on the backs of the motorists, Texans are gambling that some debt to build infrastructure is going to pay off with more businesses and more tax revenue, which it should ultimately do unless Washington crashes the economy.
Another reason we have to borrow to build roads is we waste an increasing amount money on mass transit. We should pour nothing down that rat hole either.