Spending on infrastructure is Keynesian - genuinely Keynesian, not the faux-Keynesian of bailouts, which are often labelled Keynesian with various degrees of good/bad faith.
Keynesianism is absolutely taboo in a plutocratic neoliberal economy - possibly because it's a credible reason for increasing taxation. And there's nothing a plutocracy hates more than having to pay more tax.
As you point out, in rational terms this is self-harming nonsense. Countries need repairs and they also need physical infrastructure investment. The 50s saw the Interstate system, the 60s saw generous funding for computer and IT R&D as well as other basic science, but since Reagan public spending for the public good has become unacceptable - largely because it "costs money."
As if creating jobs and valuable physical infrastructure is somehow an unreasonable expense and not basic common sense.
