Yeah, they've been doing the tracking for quite some time. Something like 80% of people prescribed CPAP machines can't adjust to using them and are non-compliant. Insurance companies are desperate to claw back some of the money spent on the machines. Personally, I would take the modem off of the device as soon as I got it home if I were worried about that sort of tracking. Personally, I use it every night so I have no concerns about non-compliance and my device hasn't had a modem since the first month I had it.
The overcharging is, sadly, the same thing medical supply companies do with literally every medical device they provide. It stinks.