I'm on medication which has the annoying side effect of dry mouth. Because of this I need special toothpaste (not covered by my insurance) and three dental cleanings a year instead of two.

My insurance will NOT cover the extra cleaning. My dentist has gone to bat for me (and gives me a discount because they agree it's ridiculous). Nobody, in their book, needs more than two cleanings a year. My dental insurance is also my health insurance, so they know I'm on medication that can make me need extra oral care.

They just don't care. And it doesn't affect them because if I ended up needing something to make up for not having had that third cleaning, welp, they won't cover that either because...yeah.

This kind of thing is soooo widespread and it IS inefficient. It doesn't cost that much to cover all of the treatment I need.