Closest I can come up with is that there's some sort of asymmetric 'value' that sometimes appears from nowhere and this throws us off a bit.
As people have mentioned, security cameras are filming me all the time - and I've no issue with that. My image has no value. It's one amongst billions of frames taken, that will be ultimately wiped, unseen and uncared about. I don't care about the image as I know the owner doesn't - there's a balance.
If one of these frames was taken by a photographer deliberately - then suddenly I care more. Why did he take it? What was I doing? Where will it be shown? To whom will it be shown? What will they think of me, based upon it etc etc.
By taking that image, they've assigned value to it - but where's the value been taken from?
Maybe it's like the wind and there's 'value' going to waste all around us and the photo is just like putting up a turbine or a sail to capture it?
Maybe it's like somebody mining for diamonds under my house - they've found some value in something I didn't know I had, but I now want my share.
Maybe it's the concept of part of your soul being captured in the photo. That photo can be shown and might provoke a response to me, but I no longer have any control over it.
Maybe it's the flip side of social media, where you can choose the thoughts and images you wish to push to the world as your representation - except you didn't choose it and you don't have a reply or delete button next to it.