I can ace those face blind tests because they don't move. If they moved, changed expressions, changed their hair, changed their angle of view, were put into a crowd of different people, were reintroduced several minutes later after seeing a whole bunch of other faces, then NO I would not be able to pass the test.
The celebrities test is always easy for me because I've seen many photos of those celebrities over the many years I've been around and have been able to imprint them in memory because of the sheer overexposure of them in print and in movies. I can do a short term memory test of faces, but insert a considerable length of time between exposures, that is like asking me to tell one tree from another, which is another thing I cannot do.
I cannot tell ordinary people apart. Everyday, ordinary people who resemble most other people. In fact, I can walk down a street and almost everyone looks like someone I remember meeting somewhere at some time. I just can't remember who they are!