Earlier quoted context omitted.
Some people lack the self control to use toothpaste regularly. For those people it's beneficial adding flouride to water.
This has to be satire. What sort of incredible self control does something like this require? Where does it end?
And that's after more than half a century of brushing teeth being a cultural expectation and something kids are taught in schools.
And that's not counting people in dire economic conditions, where frequency of brushing teeth with fluoride toothpaste is something to trade off against e.g. eating.
It's the 21st century. If we know anything about people, we know that self control and "free will" are overrated, and you can't rely on them at scale. On the contrary, you can rely on people having very predictable reactions to right nudges and incentives. It's the basis of modern economy and policymaking. It's the entire reason marketing and advertising are as big and well-paying jobs as they are. Etc.