The Stones Analogy is the best explanation I've seen for trying to help people understand what face blindness is and what it's like to live with it.
I learned one of my kids and likely my (now ex) husband have issues with this when I expressed sympathy and support for a woman online whose child was face blind and had multiple other issues. My first parenting site was called Kids Like Mine because this conversation was typical of my efforts to be supportive of others, where I said "My kids don't have that BUT..." and told some anecdote and then got directed to information on the topic.
No, my son isn't face blind but it's not normal to have trouble recognizing your own mother. I kept the same haircut for years because he used to get upset if I changed it and tell me "You don't look like you."
He was several years older than this woman's child and she had a PhD. I let him and her exchange emails via my email address and they both learned a lot.
It helped him understand himself and it helped her understand her child. With our permission, some of my son's comments to her went into her child's school IEP file to help the school understand the child and provide adequate accomodation.
People who are face blind often don't want to tell others. It's a point of vulnerability to admit "I probably can't ID you in a police line up."
But the reality is MOST people don't recognize faces and people as well as they think they do.
There are myriad videos on the Internet showing that you can swap out two people and many people will carry on with the conversation as if nothing happened, a la this video: Person Swap.
Faces per se aren't the only or even the primary way we recognize people. As the Stones Analogy indicates, one way we recognize people is via context:
Some individuals, like Anna, are always found in the same place (e.g. at their desk in an office or a school). Then it can be easier to identify them by place than by looks.
"Normal" people who are not face blind may fail to recognize someone they know if they run into them in a different context. My understanding is this is up to fifty percent of the time.
I have experienced this myself. I once ran into someone in a taylor shop and we BOTH were like "You seem familiar. Don't I know you?" It took us several minutes to figure out that she was a nurse in a doctor's office in a different city where I was a patient once every few months.
I have read that if someone is held at gun point, their entire focus is on the gun. They can describe the gun in great detail and may not be able to describe the person who was pointing it at their face.
It's a mistake to think that if someone is face blind, you can do any damn thing you want to them and get away with it.
Face blind people often recognize people they know in person by other features. Many of them are good at recognizing voices, much better than average in fact.
In the movie Places in the Heart, a blind White man stops the lynching of a Black man by calling the robed KKK members by name. He doesn't care that their faces are covered. He can't see their faces anyway but can ID them and would be a credible witness in court.
In the movie Wait until Dark, a blind woman takes control of the situation when criminals are harassing her by waiting until dark, sabotaging the lights in her apartment and dousing her assailant in gasoline so he can't light a match. In the dark, they are on her turf and she has the advantage.
If you have a child who is face blind or has trouble learning faces: It's socially impairing because they have trouble with something most people take for granted, but I would not make too much of it because most people are not as good at recognizing faces as they think they are.
Historically, humans lived in small villages and didn't know that many people. With eight billion people on planet Earth, we all are finding ourselves in situations that our wetware wasn't designed for and it causes a lot of problems.
This is where it helps enormously to focus on the child being differently abled instead of disabled.
It's extremely impairing if you want to force fit them to what works for YOU or what society typically expects. It's not necessarily a big deal if you let them do things their way.
FYI: Face blindness is not a big deal if a lot of their life is online. Facial recognition is not the primary way we identify people we know on the Internet.
My ex husband was career Army where the same short haircut plus the same uniform make it hard for most people to recognize any particular individual. This likely helped him cover up his problem at work and also your uniform has a name tag. If he couldn't quite figure out who you were, he could call you by the name posted on the front of your uniform.
My ex likely was about as impaired as our sons in various ways but was talented at finding life choices that made his issues no big deal. He never sought a formal diagnosis and official accommodation for his disabilities at work because that's a good way to limit your career.
Instead, he pursued things he was good at where the things he struggled with hardly mattered.
I'm pretty sure "White male privilege" and "having a serious career, so I can't be expected to do a lot of things that are BENEATH me" is something many successful men fall back upon as a cover up for the fact they CANNOT do certain things and don't want to admit it.
Officially, fifteen to twenty percent of people are "handicapped" but studies show that around sixty percent of people would benefit from various forms of "accommodating design."
I know all that in part because I never told my kids "You're disabled and shouldn't dream big." I told them "It's a TRAIT and has both good points and bad points. Figure out how to play to your strengths and work around your weaknesses."