How long does it take to turn off a light? Perhaps a couple of seconds, depending on how far away the switch is. How much energy does it take to turn off a light? I'm not going to guess, but it's an incredibly small amount compared with energy we consume on a daily basis.
My point is that having automated lights, or those that turn on and off at a verbal command, are not going to save us huge amounts of time: certainly less than a robot vacuum cleaner (1h per week) or a robotic car (1h per day of time that can be spent doing other things). Nor are they going to save us lots of energy (compared to say the benefit of a lift in a tall building). And yet we still want them. Why?
My suggestion is that it's not just about the time taken to do a task, or the effort expended doing a task, but that there is a cost to humans per task that is independent of time, effort, difficulty, etc. It's a kind of mental exhertion. I appreciate that this is unscientific, but that's where good science starts - with a hypothesis like this and a goal of measuring, proving or disproving.