You’re wrong on both counts. The geology of many areas cause excess fluoride in well water without any government intervention, which can then become worse when using fluorinated toothpaste. It’s rarely a significant issue in the US, but gets far in some countries.

“These sources include drinking water with fluoride, fluoride toothpaste—especially if swallowed by young children” Ie: swallowing makes it worse but the point of fluoride in toothpaste is to be absorbed, so some will get absolutely even in those who already have issues.

https://www.cdc.gov/fluoridation/faqs/dental_fluorosis/index....