Actually the cost of initial construction and future reconstruction is about the same. The problem is the initial construction is heavily subsidized either by State or Federal "growth" grants, or by developers who financialize the whole thing through the sale of federally subsidized development loans.
In theory what should happen is the resulting development pays enough taxes to pay for all the infrastructure it depends on to be rebuilt as needed (typically every 15-30 years depending on which kind of infra we're talking about). But in practice the taxes are not actually linked to the cost of infrastructure (they are much too low) and not enough funds are collected to maintain the infra.
This is managed by a shell game where fees from new developments (who just financialized their new infra) are used to pay the maintenance on old projects that are losing money, and where federal subsidies for growth and expansion are contorted to uses like widening a scarcely used road that is falling part (bc. the feds will pay to expand but not to maintain) - which solves the problem for now by making it even worse for the next generation.