The Model 3 can be put into drive by a two year old with the door open, no weight in the seat, seat belt off, and the phone key does not even need to be in the car.
^^^ This
Video evidence:
Model 3 Rollaway
This is a "corner-case", rare issue, but with possible major consequences, and I would imagine it will be addressed by Tesla, as it should be quite easy to solve (they have all the protection there already, it is just not complete). I have reported the issue to Tesla, to deal with as they see fit.
Parents with 16 year olds should be using Pin to Drive as well!!!
That is extremely unlikely to be effective. 16-year-olds are actually quite smart. If you are worried about your older children driving your car, your only options are to do all of the following:
1) Turn off Phone As Key
2) Pick new, secure credentials for your Tesla account and ensure your security questions cannot be socially engineered by your progeny. If 2-factor authentication is possible and provides protection against social engineering, use it.
3) If you have an Apple Keychain or other keychains, be sure your Tesla credentials are not being propagated to an extra device which the teenager has password access to.
4) Keep All Key Cards and Key Fobs with you at all times, or in a locked, secure location.
5) Keep PIN-to-drive on as final protection, and change the code frequently.