but dental is usually not included and most people pay it themselve

Children under 18 are covered for almost all dental care under the basic Dutch health insurance and therefor free of charge.

https://iwcn.nl/living/healthcare/dental-care/

So you are wrong, you had free dental as a child, the fluoride is aimed at children who are not guarenteed that in the US, it varies state to state and depending on your income.