Doesn’t need to be microphones. Just time of day.
Let’s say someone brushes 3x per day, exceeding the basic expectations most dentists want to see. First brush around 10 AM, second around 7 PM, third around 2 AM. Logically, we can assume this person is more of a night owl who gets up late, brushes after they get home from work, goes to bed late. Insurer correlates the “night owls are slackers who DIE, DIE, DIE because they’re slothful, lazy, awful horrors who sleep late” hysteria that comes from sanctimonious morning people with this disgusting person who brushes 3 times a day, but not at socially approved hours. (And maybe on weekends, first brush is noon, second is around 9, third is 3 AM.) It doesn’t matter if this person works swing shift or tutors children after school or is a child psychologist who specializes in school age kids (and therefore works after-school hours) or is actually just a night owl who isn’t functional before 9 in the morning, or is not a night owl at all, but is an extreme morning person who wakes up at 2 in the morning and goes to sleep at 7 pm.
Now let’s assume this person has an accident - say, a car accident - that results in a couple of cracked teeth. (Happens all the time.) Leaving aside how bloody difficult it is to get car insurance to cover dental repairs (narrator voice: it’s really damn hard and often isn’t possible at all) the sleeping habit correlation gets tossed into the mess of liability and coverage. Even if that hypothetical car accident happened at 4:30 PM on a perfectly clear spring day, let’s watch the insurer’s attorney argue that the victim is actually at fault because they’re lazy slackers who sleep bad hours, so were clearly at fault, and then ta-da! This is now legal precedent.
I wish I was being more dramatic than just for funsies. (I am being a little dramatic. Most morning people are merely irritating and obnoxious in their self-perception of superiority.) But the issue of bad science becoming legal precedent is a real one, and crappy correlations being exploited for corporate gain is just SOP.