Or, even cheaper, you just dismantle the "hail cannons", since there is no scientific evidence of their effectiveness or even a hypothesis on why their working

Or, even cheaper, you just dismantle the "hail cannons", since there is no scientific evidence of their effectiveness or even a hypothesis on why their working principle would have anything to do with hail. So since they do nothing, have never done anything, you clearly didn't need them in the first place.