I agree with that. However, some things might be easier to fund with charitable donations than others. For example, the reason GiveWell doesn't recommend donat

I agree with that. However, some things might be easier to fund with charitable donations than others. For example, the reason GiveWell doesn't recommend donating for vaccination campaigns isn't because they don't think vaccinations are cost-effective (they are) but because giant organizations like governments and the WHO are funding these things already. It's not a "neglected" cause so it's hard to move the needle by donating there. I suspect that hard infrastructure like railways are funded by loans from the IMF and maybe foreign aid? I don't know if GiveWell has evaluated that sort of thing specifically. GiveWell's mission is advising individual donors on which charities they should give money to, which means charities that exist, take donations, are trustworthy, can show effectiveness, and so on. It's not things people could theoretically fund; it has to be practical.