Comment by nine_k

I grew up with a father who was obsessed with the idea that we were wasting electricity by accidentally leaving the lights on sometimes. As a result he's spent probably thousands in attempted energy saving devices which have all not worked and definitely would never save enough compared to the cost of them.

Which is why I think about these things despite this seemingly obvious solution.

And the fact that the guest bathroom when I visit his house still has no light switch but does have a cheap motion sensor which is annoying as hell.