I can't remember people's names well until I know them quite well, and I'm very slow to make new friends and to identify new enemies, so in practice I forget the names of most people I'm introduced to, usually within a few moments of being told the name. Surprise, surprise.....I can't remember things I have no direct interest in. Do I care if a complete stranger is called Herbert or Horace?
I don't think it's intrinsically a memory problem. I think it's more to do with focus. What you don't focus on, you probably won't remember. What you have no direct interest in, you won't focus on unless you notice an indirect interest (such as "hey, those people are potential friends at least, and if you never make the effort, you'll make no friends at all, and then where will you be?") and then feel motivated enough to override your natural impulse. The other factor is anxiety, which can make it very hard to focus at all.
Celebrities? I don't care enough to remember their names, usually. Entertainers - if they entertain me well, I tend to remember their names better, though I'm often stuck and can't recall the ones who I thought were pretty good, so it could still take a while. Ditto for names of films and TV shows. Also song writers........as a musician I often perform covers, but I hardly ever credit the writers, even though I really admire their music.....that's downright discourteous of me. But then, I'm too busy making sure I don't screw up the performance.