The problem is that when you make it rain, you are actually robbing rain from the people downwind of you. It is the same principle as building a dam, but with rainfall instead of a river. Depriving another nation of water is a hostile act, which is why there is so much secrecy surrounding chemtrails.

Even within a nation, who will pay when making it rain on fields causes wildfires and flooding that destroy homes and kill people? They aren't going to admit it despite it being right in everyone's faces.