There really isn't any need for them to warn users as there should never be anything to warn about. Look at some of the profoundly radical UI revolutions we have seen in recent decades:
- DOS -> Windows 3.1
- Macintosh -> Mac
- Windows 3.1 -> 95
- Windows 95 -> 7
- (nothing) -> iPhone
Did anyone warn us about those drastic UI reinventions? No.
Because the designers at Apple, Microsoft, etc. actually had PC's and Macs and stuff with which to test their new creations so they were able to make drastic changes that were quickly embraced as drastic improvements which were so intuitive that only a minimal learning curve was ever needed.
But at Tesla not a single member of the UX team actually owns a Tesla (I assume). They take the BART to work and zip around on hoverboards and have absolutely no idea what kind of device their code will end up running on.
Tesla would be wise to provide some loaner cars to their UX interns so that they can get a better idea of what cars are and how they might be used.