I'm almost the complete opposite of the OP. Unless I actually spend time with someone, or interact specifically with them on a regular basis, I couldn't pick them out in a crowd.
Facial features just blur together for me. I swear, I'd be the most useless witness to a crime, ever, if I had to describe the assailant.
"Well, he was a guy... with a nose...". I'm THAT bad.
Similarly, on multiple occasions trying to advise police regarding local youths harassing the wife and I, I could only describe them as "dull-eyed inbreds in tracksuits". She can tell some of the ones involved at a glance... I could walk right past them and not even know, even though I saw them kicking my fence in the night before.
I don't know what it is, but I just have some kind of mental block that means I simply can't recall random faces at all.