They're incredibly common. I can't get the radio in my car out of certain modes I accidentally get into. It doesn't even have an off button. I essentially have to wait several minutes until it times out.

Many devices I have, once I lose the manual, are simply impossible to use because of the points listed above. My dashcam is simply impossible to use because of this, even though it has a bitmapped display. All it needs is power, menu, up, down, select and with a bitmapped display you can do anything with that. But noooo...