You're talking about different things here. The Australian "smart" gates mentioned by the previous poster are border control, and they work by validating a picture your face against the picture in your passport.
YMMV, but I actually find using the smart gates much less invasive than dealing with human immigration officers. The gates do exactly one thing and that's that, whereas with officials there's always an uncomfortable "guilty until proven innocent" feeling (where are you going? where are you coming from?) coupled with the knowledge that borders are largely civil rights free zones, even for citizens.
YMMV, but I actually find using the smart gates much less invasive than dealing with human immigration officers. The gates do exactly one thing and that's that, whereas with officials there's always an uncomfortable "guilty until proven innocent" feeling (where are you going? where are you coming from?) coupled with the knowledge that borders are largely civil rights free zones, even for citizens.