I mean, true, "SHANNON" is more or less common as a first name depending on where you live. But no matter were, in North America, it's not an unheard of name.
Perhaps it's that it's not all *that* common a name that makes people so incapable of noticing a slight variation in spelling.
"Shannon" is the name of a city, a river and an international airport. It's also a not uncommon last name, or first name. My name is "Shannan" spot the difference? It's small, true. ShannOn is not my name. ShannAn is.
Seriously, there are people I receive regular emails or other correspondences from who, after months, even years, cannot seem to see that every time I write to them or reply, I sign ShannAn even though every time they write to me the address me as ShannOn...
I don't want to do the snarky "FYI, my name is spelled with an 'a', not 'o'" to either the president of my library board, nor the president of the ALA division's board I'm on... But seriously, I am the only one who checks to make sure I'm spelling someone's name correctly? Perhaps I'm more sensitive to checking how someone's spelled their name in a message before replying because of how badly my name is regularly butchered?
*sigh*, here ends rant #382 regarding my pet-peeve #427