Health

"Concerns around excessive fluoride intake are one reason why some countries have chosen not to artificially fluoridate their water supplies – but only because their drinking water already has naturally high levels of fluoride."

Other than that, people complaining about their personal liberty. It did say some countries fluoridate other things like milk.

Still seems there is universal consensus from those with a brain, that it makes sense to have something, particularly drinking water, as a source of fluoride.