You'd almost think that civil engineers have an economic incentive in improving infrastructure!
I was thinking the exact same thing while walking on a bridge in Cleveland built in the 20s and stumbling on a hole in the bridge deck, while inspecting access for an entirely unrelated project at the site.
Stinger, the problem is multi-fold. American infrastructure is pretty old. America's utility infrastructure is borderline ancient in many cities! While bridges aren't falling down everywhere, they are certainly being stressed via overloading the original design loads to allow more traffic, eating into the safety factors, and corrosion. The Cleveland Innerbelt bridge was dangerously nearing a collapse scenario. It isn't often that a DOT shuts down the most important Interstate in a large city. The bridge that had collapsed in Minneapolis was so far gone, that the Civil Engineers pretty much stated it was almost too risky to try and fix it as that could have precipitated a collapse.
All structures have an expiration date. It seems odd that people dying from a corroded bridge collapse wasn't enough to convince people that "yeah, we need to address our infrastructure issue".