I've always wondered about people who say that... there's enough light (particularly when it's not a new moon) to see to go the bathroom, but maybe my eyes adjust to the light better?

Unless you use shutters so the room is completely dark

You must live in the city.

I live in a rural area.

Do you have to turn the light on to use the toilet?

Gotta look for large spiders under the seat.

In HK village houses the spiders are outside ... we look for snakes swimming up from septic tanks (yes they are still used even in some new village houses) or coming through bath drain that goes to outside drain (yes still a thing).

Hazards of living in Australia ...

I do have to, this is why I bought one of those IKEA smart bulbs and made it dark and blue. If I get up at night, I use my watch for light.

Why blue and not red/orange?

I did have red but it didn't feel as good as blue.

I've also read somewhere that even the US Navy is changing to blue in their ships for some readability reasons.

No but I think many people in fact turn the light on when using the toilet.

Buy one of those darkness-sensing nightlight plugs and leave it in the bathroom. They cost under a $1 a month to run.

I use iPhone flashlight on mild mode…

Red light