No, silly. It's because the other races just aren't beautiful enough, or they are too beautiful so that it wouldn't be a competition.

same reason as to why the World Series is only played by american baseball teams - every other team sucks

Nope... They're not come here because they have jet lag... So they all got disqualified

What if every other alien race has also a Miss Universe competition and no human appears?

No actually, we are just being boycotted. They have issues with how we do things.

Asari aren't allowed to enter or they'd always win.

I'm not sure if a bacteria qualifies to enter any election of miss universe etc..

By the time the competitors from other planets arrive they aren't beautiful enough to compete. Travel time too long.

No, just that our women are the most bangable in the Universe. Aliens agree too. The Japanese have solid proof of that.

I won, Thank you.