Hydro is capital intensive up front. In the west where the capital is available basically all viable locations have already been dammed. It also requires the infrastructure to transmit the electricity and the demand for it. That’s not to say there is no place for hydro power, I just don’t think it fits the conditions of many global south nations right now.

I think it’s also worth mentioning that a lot of the areas flooded for hydro reservoirs in the west were just forcefully cleared of inhabitants and the negative environmental impacts were ignored. Formerly colonized nations will go about this differently.