Unless you weren't the first owner of the car, then chances are you lucked out on one they put them on. While I haven't heard of many saying this, you aren't the only one, so apparently it's a thing on some cars. I didn't have rear ppf or mud flaps on mine. It isn't like Tesla to throw in extras for free,
There have been lots of odd things, like MYLR coming equipped with MYP drive units probably due to lack of the other drives temporarily dumbed down in software. We know this because we have owners posting pics of serial numbers that had the P numbers and not the LR numbers.
In this case the mudflap generosity seems to have been limited and stopped.