Everyone has something to hide.

Consider, you and your lover are in the midst of intimacy, quite nude, quite passionate: if you have nothing to hide, why would you object to your next door neighbour taking a video of your procreative exercises?

Or: have you ever picked your nose and looked around to see if anyone was watching?

What about your bank card number? Do you mind not hiding it from me?

Everyone has things that should not be publicly accessible.