I think he's referring more to the fact that "semi-intelligent" systems like automated thermostats and light switches have a difficult barrier to cross when it needs to determine your intent from it's sensor readings.

For example: Your Nest thermostat doesn't see motion in its camera range. Are you really out of the house and it's safe to turn down the heat? Or did you just go down to the basement to do laundry and took a phone call? If you set a time threshold, is it enough? Not enough?