Some places regulate the use of coated rebar to reduce corrosion risk. We could also use stainless rebar. The real problem is that there is not many incentives to construct things to last, the implicit assumption is that we will want something different in <100 years, so why build it to last? You could do lots of things to increase building life, but fundamentally people want things built cheaper and faster with the latest stuff, and don't care about long term implications. Although I wish people would care about these things, the truth is that it is the minority who do.