Ask Lemmygrad

They don't 100% avoid it, but the point is that after the thing is built, both the damages and benefits are felt mostly by the same nation. Nuclear on the other hand requires a stable stream of material, and it's a privilege usually reserved to technologically advanced nations. Third world nations on the other hand can afford to build their own dams, like Brazil or Ethiopia.

Like others pointed out, hydro (dams) are a mess for the environment too, but you can't build a dam in Africa and export the energy to Europe. Uranium can be exported though, and that's how it's implemented currently.

I'm not against it as an ideal, just that the discourse around it often ignores the current material conditions of it. The countries that can afford to move their grid to nuclear are either huge and advanced like China or Russia/USSR, or rely on blood uranium from their colonies.

But I'm happy those two are helping out and it might eventually be universally feasible, even if from my naive position I'd prefer a >90% green grid.