A good starter would have been running the keyfob data on a different CAN line than the one going into the headlights... you know, the one you can reach with your hand from the outside.

Then we could also talk about encryption, but at least making it a tad more difficult to have physical access.

Not that toyota is the only one. If you ever notice a car that has a reinforced grill protecting the front RADAR, or the rear lights... now you know why.