Family restrooms?

So we were at the mall yesterday and needed a pit stop before hitting the highway. On our way out we stopped at what we thought was a restroom. Well in fact it was - but a "family restroom" - which was a multi-unit bathroom but it had a locking door. I believe the intent was for parents with kids to be able to take them to do their business without having Dad sneak his baby girl into the men's room or vice-versa for Mom...

Of course real world application was very different. Teenage guy exits the bathroom and we start to move towards the door - then teenage guy pulls the door behind him as he exits. Apparently there was someone else in there! Moments later teenage girl exits and they walk off together.

I have this sneaky suspicion they weren't family and teenage boys and girls generally don't go potty together so unless they were kissing cousins I think I know what they were doing in there together (gag)

Yet another reason to avoid public restrooms all together! LOL