> Great, it has expensive royalties and it betrays the user.

Your cell phone also sends out photons that can be spied on. Worse yet they're multicast so multiple parties can receive them at the same time.

Seriously though, this is an absurd concern, and I say that as someone who is very privacy minded if not actually paranoid.

I still don't trust that cell phones aren't sending back keywords picked up on the microphone, but I guarantee you that right now no one is listening to your digitizer's rf output, much less that the device itself is somehow "betraying the user" by exfiltrating anything over it.

Yeah I mistook rf for something else

Short range analog RF signal to detect where the pen is, not something containing digital information. Your toothbrush motor and charger probably has comparable level of RF radiation come out.

They do, but it should be noted that there have been reports of toothbrushes exfiltrating accelerometer data so toothbrushes are no longer a good example of an innocuous device.

What possible use would a company have for knowing when you pick up your toothbrush? What valuable data can they extract from that?

Maybe letting health insurance companies know their client(s) aren't brushing their teeth "enough" (by some metric), thereby setting themselves up for increased dental costs?

Probably the same thing for people brushing their teeth too much?

Ah I misread that, thanks