An excellent question. The "traffic engineer" profession is deeply broken. https://www.nytimes.com/2023/01/06/us/widen-highways-traffic.html
Widening Highways Doesnโ€™t Fix Traffic. So Why Do We Keep Doing It?

With billions of dollars available to improve transportation infrastructure, states have a chance to try new strategies for addressing congestion. But some habits are hard to break.

The New York Times

We now have overwhelming evidence from a million different directions that sprawly car culture *doesn't work*. Suburbs don't pay for themselves. More lanes don't decrease traffic. Stroads kill people & inhibit economic growth. Parking is economic deadweight.

We refuse to learn.

The whole car/sprawl complex has reached such size & momentum that it just thunders on despite all this evidence -- one of many ways the US punches itself in the face over & over again while bragging about exceptionalism.
@drvolts
Part of why suburban sprawl continues is that it solves some problems, they just aren't problems that really have to do with housing. Suburbs are a way to keep some of the middle class afloat in the face of wages that aren't going up through homeownership and home values that are perpetually increasing much faster than incomes. For policymakers this has been the solution that enables their total refusal to address inequality in the distribution of the benefits of economic growth.
@drvolts
And that's just one problem it "solves", there's a whole raft of things that should be addressed directly that sprawl is the solution to.
@Lacci
The United States mostly papers over cracks policy wise. We rarely can get ourselves together enough to address pressing problems so we often go all in on non-solutions.
@Lacci
Sometimes we do manage to address things directly, but mostly we've succeeded in kicking the can down the road. So for example instead of fixing healthcare long term the ACA made enough improvements to offset encroaching healthcare issues for perhaps a decade. It was a huge accomplishment, but healthcare is a crisis still in 2023.
The percentage of the population that is uninsured or has insurance so bad they can't afford basic care is higher in 2023 than it was in 2010. The uninsured rate is a bit over 10% instead of 12% in 2010, which is huge for those millions of people if they have a catastrophe. But 5% more of the population is underinsured now. It's much better than it would have been had we done nothing, but not close to good enough. And that's about as good as it gets in US policymaking in my lifetime.
@Lacci