What could Tesla possibly do to provide more safegaurds? Measure resistance on the steering wheel to prove it is flesh on there? Driver-facing camera? Weight sensor in the seat? Each of these has their own issues including defeatability and privacy invasions.
Anything can be defeated eventually. However any attempts to be defeated should automatically put the liability on the person making that attempt. Example: It is not Samsung's fault if I intentionally disable safeguards and over charge my battery causing a fire or explosion.