That's a very wrong way of thinking about the problem. It's not actually a human error except in the strictest sense. Imagine if the mechanism for flying an airplane involved a thousand different levers that all need to be carefully moved in concert in order to avoid crashing. Is crashing such an unflyable plane a "human error"?

The problem here is that browsers allow overiding ctrl-f and almost no users realize this is possible. It's not just a human problem, it's also a browser design problem. Browser makers have trained their users to trust that pressing ctrl-f will pull up a find dialog, it's as much their fault as it is user's fault.