Infrastructure, whether broadband or highways, has positive externalities that are hard for infrastructure builders to capture, so the free market under-invests in infrastructure. However, government investment in infrastructure also is distortionary and needs to be considered in every instance.

For example, it's great that we can get products delivered overnight from Amazon. However, as you point out, that is effectively a public subsidy of Amazon's business model, and that has negative effects too. Subsidizing public road infrastructure makes shipping products across the country artificially cheaper compared to making and selling them locally. That essentially strips away an advantage local retailers and manufacturers would otherwise have against big, national companies like Amazon.