Why do China mm pic shown with ID card?

babyme

Notice lots of mm pic on this site from video download shown with ID card.
Is it to prove that she is above legal age?
But it is hard to see the card.
If one can see the age on the card, that means the name is known too.  Are they afraid that they are known to friends and relatives etc ?????
Anyone thoughts please.

BTW, some ID pic shown on Left and some on Right,  are they not the same always?