To collect as much customer data as possible, to (hopefully) anonymize it and bundle it to sell them to data brokers and extract more money from their customer base...

All of it with their "consent" (you installed the app and likely accepted their ToS/PIvacy Policy), under the pretense of providing them a service like counting the time/frequency of your interaction with the product or reminding you to use it (something you would already do anyways, maybe less accurately, if you are a functioning adult).

(Hypothetical made-up example:) "Dental" chewing gum companies would pay $$$ for info on peoples' brushing habits crossed with demographics and geographical data: if the data shows that there's a particular city or county where people brush their teeth 25-50% less than the general population then there's a good bet they should increase their ad-spend in that area, because (let's say) people who don't brush their teeth are more ameneable to buying dental-gum to offset the damage of not brushing.

They show you if you have spent sufficient time on the front, top, and back of each tooth. Electric toothbrushes are used differently than manual brushes (you don't move them back and forth).

tbh i was wondering the same thing... brush stats, time per tooth maybe?

the one reason I have used the app is for my kids. it plays animations while they brush and keeps stats and let's them pick avatar colors and stuff as rewards.

Because it's cool man!

BTW, I stayed over at a friend's place one time, and he donated me a new electric tooth brush. How can people even use this? I found it extremely hurtful on my teeth. I would not use it if you paid me.