I'm not at all against people automating the hell out of their homes, so I'm on "your side" as it were, but this isn't the greatest argument in favor.

People yelling at family members over leaving the lights are essentially "penny pinching" fractional cents of energy costs. I'm sure all the computers, sensors, networking gear, etc, that make this all work consume significantly more power than if you were just to leave every light in your house on 100% of the time, especially if we're talking about LED bulbs.

That isn't really accurate. An Aeotec Smart Switch 6 for example consumes <0.8W, while a single LED lamp consumes 4-20W depending on brightness. So the lights in a single room could reasonably be consuming 20-100W, vs. a smart switch consuming <1W.

You don't have to optimise your usage much to totally offset the power cost of using smart devices

My kitchen, with all of the light sockets populated, is 45 watts of LEDs, and it's not even a modern-sized kitchen.

That switch stays on fro, sun up to bedtime.

It's interesting that people are real sticklers about turning off unnecessary lights. As you said, the electricity costs are negligible. Today's "bulbs" are either CFL or LED and they consume virtually zero electricity. But I still have this itch to turn each one of before going to sleep.

You're going to need 10 watts to light even a tiny room with a single bulb. You can run a raspberry Pi (not even really designed to be low power) on half of that.

If your house is so small you only need one bulb per room and has a couple of rooms (i.e., you live in an apartment), where the light is fove feet from you, nobody is going to market a product for that.

As the other responder said, you're still in for at a minimum 20 watts in a room for an actual house. Further, you pay for those watts again if there is AC (so more like 25-30 watts), the lights might not all be tied to the light switch, and they may not all be rooms you frequent. And then add on that rooms you don't frequent may still have incandescent bulbs in them because you stopped, like me, after replacing 20 or 30 bulbs and you're replacing the rest as they burn out.