We prepare for going out into public view. We act, thus we perform for the public. We put on a suit and tie (used to), make up (still, mostly), shave (not often enough). We do not walk out in our underwear or pajamas (scratch that, some do). We behave. We do not show our emotions openly and loudly, we do not cry, wail, or scream (although we often feel like that). We act/perform appropriately. We put on our Sunday best, and a pleasant facade and off we go into public view. We know we will be seen and judged. So why then uncomfortable being photographed as such when we actually are prepared for the public? Even those who walk out in their pajamas, unshaven and grumpy know they will be seen and judged. They just do not care. In which case they don't (or shouldn't) care being photographed.
I have much more respect for some primitive cultures who fear that being photographed will steal their soul. I get that. On the other hand, I feel like punching (just feel, wouldn't do it, of course) anyone in the contemporary society who complains about being photographed (or their children) in public.