Sometimes that infrastructure is only worth pennies due to associated debts, and restrictions that governments impose on laying off unproductive workers.

If it's sold on a market, then it's value is it's sale price. Competing investors want to make money too.

Well, according to market proponents anyway. I think we should stop treating them as economic oracles and consider other forms of valuation as well, like the marginal cost to the population if the service and the jobs it provides didn't exist.

Obviously people who are potential bidders in a market are heavily incentivized to downplay the value of what they're bidding on, so it's not clear to me why their metric of valuation should be privileged above all others. It's just like the idea that efficiency should be conceived of in terms of minimizing production cost, without regard to the effects of that approach on customer/employee retention or organizational resilience - partly because those second-order effects are a little harder to measure, partly because owners have an economic incentive to promote that particular definition above all others.