Auto locking when driving off has become illegal due to the introduction of an ADR that basically states that in an accident all four doors must be able to be opened from the outside after an accident. When they crash test the vehicles, there is obviously no one in the car but under testing conditions if there is auto drive away locking, the vehicle cannot be opened from the outside and there for does not pass that particular ADR. There were a couple of recalls on cars that came out with the function, but then had to have it permanently turned off.
This was discussed a while back, see thread below:
https://www.fordforums.com.au/showth...ight=auto+lock