Helen
Implicitly explicit
Helen, never underestimate the power of forum-goers to be needlessly pedantic. I have seen people criticize other for assuming people will understand they are speaking about an American President. It's one of the reasons I often use the -OTUS names (POTUS, COTUS, SCOTUS, FLOTUS [first lady], VPOTUS, et al.)
Well, I think you have hit on one of the eternal truths here. If not the only one
"Did you hear what Obama said on TV last night?"
"Obama, Obama who? Kevin Obama, who runs the corner shop?"
"No, the POTUS!"
"Oh, the POTUS, now I see!"
And there are indeed other people mentioned here often enough without any explanatory titles, far less famous than this POTUS guy.
Well, I guess I will just have to remain puzzled. But not to worry, I've been puzzled for most of my life, so I'm used to it.
Or perhaps I'll just go with Earthborn's explanation