My grandma, born in the 30's, isn't any good at computers or technology in general, and has trouble operating even the simplest TV remotes and cordless phones.

One thing she can operate is her HP-12C calculator. At the time of it's initial release, someone taught her how to use it, knowing that the RPN interface would be much easier to teach her than infix notation that was equally popular at the time. She never figured out infix notation, at least for more than single operations.

Pretty much everything uses infix notation now a days, so that's what everyone learns first, making RPN an additional skill that usually gets passed by.

It's interesting to learn that there was a time when a calculators interface was a toss-up, and some people learned RPN because it was the easiest to learn, as opposed to it now being an additional skill that would conflict with earlier experience.