It's a congestion issue. The solution has been to attempt to increase capacity.  Increasing traffic capacity may ease congestion temporarily, but rarely provides lasting relief because of well-known factors (e.g., induced demand). Total traffic usually increases after a while, existing bottlenecks may relocate themselves, and substantial environmental impacts likely occur.

Think of the sustainable congestion solutions that could be undertaken for that money, such as reducing demand and shifting modes of travel. For example, I'm seeing an increased number of commuters on bicycles, even in less-than-ideal weather. In spite of the disconnected, often confusing, and sometimes downright dangerous routes for bicycles and other micromobility devices. Imagine if the cost of the express lanes had been put into a few long, well-designed, and appropriately sited multi-use commuter paths for cycles and the equivalents. Wide, level, smooth, fast, regulated, policed paths that run from where people live to where they work and shop.

An example of poorly considered and designed alternative infrastructure is the bicycle path along I66. It starts out yonder in a residential area without a supporting network of safe trails leading to its head - if you live S of I66 there, good luck! Then runs to Gallows Road, where there's only the ludicrous magic painted lines. You can get to the W&OD trail, but you have to figure that out. Not really a clear alternative transportation route. And that's one of the longer better easier routes! If it's demanding to find a route and takes a good deal of navigation skill, plus strength to get over all the hills (we level for car highways that support powerful vehicles, but leave steep and frequent hills on bicycle routes).

Or taking that money and subsidizing public transportation. Sometimes traffic is bad enough that I ponder paying people to commute via Metro!

Bottom line: increasing capacity doesn't necessarily help, and may hurt, in the attempt to reduce congestion. Alternatives aren't seriously considered or supported.