Hi,
To me the number seems low. I think perhaps people may not seek help for phobias and therefore the cases are under-reported. Also, if people suffer from agoraphobia or social phobia, they are not likely to be noticed because they don't go out. These people are literally hidden from view.

After reading your piece I looked up some material about phobias (yes, you got me interested). Found a great article. It suggests an occurrence somewhere in the 12% range. The article was written in response to a case that had been undiagnosed for maybe 50 years. The patient suffered from tomophobia, which is very specific: fear of invasive medical procedures. If the individual hadn't needed medical care, this case never would have been discovered.

I wish I could help your mother...I'm quite old and find electronic devices enrich my life. Same for my husband.

I think it's wonderful (as @abigail-dantes says) that you are willing to reach out to your mom. Perhaps if you explain the problem in terms of your own fear, that you fear losing contact with her, maternal instincts might win the day. In that way, she is in control and helping her son. Moms are really susceptible to the needs of their children :)

Good luck... again, let me say that this is a helpful article. Many people may have family or friends with this issue and your article increases understanding.