Perhaps a more likely (still unproven) statement is they "dont know about it, or how to use it.. YET". Until it appears in their local store, with a User Interface such that they can put their $100 note in, and type "Email to Aunt Flora in Wales - Subject, Happy birthday from Joe In America", they probably wont either.
And then they find out a few days later that Aunt Flora never received the bitcoin, because there was malware running on her machine that hijacked her private keys. Maybe she received a phishing e-mail earlier that said, "Bill Gate will send you free bitcoin if you click this link and then forward the e-mail to all your friends!" She was using Windows after all.
And who sends cash to their aunts anyway? Why not buy a gift card like normal people, or even just send a check in the mail if you really insist on the cash?
Bull-tards love to give silly examples of why the world needs bitcoin, but for each one there is already a better solution in place, or it's not a genuine problem to begin with.
ie. there are very few people interested in being "their own banks" because the bank does everything for them they want, and they don't need to worry about losing all their cash on a misclick or technical issue.