There's a tiny amount of light, yes. I don't know why Amazon made it that way. It's not really visible.. not to me, at least. But it's probably one reason the battery is slowly drained, over weeks, even if not in use.

It does turn off when you're not using the kindle. But you can't turn it completely off while reading.

I suppose the use case is picking up the kindle at night in a dark room while you disabled the light when you were reading outside during the day.

If you put it in / out of sleep mode juuuust right, you can trigger a bug (race condition?) where it doesn't turn the backlight on.