Why don't people eliminate all cuckoos?

As you all know, cuckoos are birds whose entire existence depends on other birds. They lay eggs into other birds’ nests and let the other birds do all the work for them. Even worse, their chicks kill all the chicks in the nest and force their “parents” to raise only them. And that’s not all, some species of cuckoos even form gangs and will threaten other birds to do the work for them, Mafia style, so there is no fighting back either.

As far as I can see, cuckoos are dangerous parasitic species. They threaten the survival of other birds and can potentially drive some species of birds into extinction. But I’m baffled that no one seems to do anything about it. Googling the question in the title brought up nothing. With such a dangerous species with aggressively invasive lifestyle like this, I would expect people to treat them as pests and curb their population. But that doesn’t seem to be what I’m seeing. Why aren’t people concerned about cuckoos?