That's fine for freeways that people are taking across multiple states. When trips are too long to work as commutes, the level of traffic is low lower and you're immune to induced demand from everyday traffic.
But this is about the roads that get you around a city. If you make those roads a lot wider, but the housing density drops 3x, your ability to visit family doesn't improve at all.
Increasing the distance you can go in 6+ hours broadens horizons. Increasing the distance you can go in 30 minutes inflames sprawl and congestion, unless you have some kind of efficiency miracle to apply to the construction.