I’ve wondered this too. But maybe ux is more important in this case than privacy. There’s a red or blue bar that shows up when mic or location or hotspot is on. I’d hate to see that when my full screen camera app opens. But I do value privacy. So another solution would be what Mac has implemented. A led shows up whenever the camera is on. But I’ve seen reports and articles where it’s possible to fire the Mac camera and shut it off quickly before the LED has time to kick on. (I cover my Mac camera with a post-it).

I don’t know what the solution could be. Maybe a vibration of a specific kind?

I think Apple should address this. It’s a good next step in terms of privacy focused Apple and it’s something that will be rewarding for the user to see that whenever the camera opens, something happens. Good PR points for Apple. A win for the user.