Santa is magic. That's how he's super fast. And he doesn't cover the whole universe, I think, just the Earth.

Still, he's magic and runs on the belief of kids, so he probably could cover the universe too.

One of the American air defense forces runs a Santa Tracker every Christmas...

[He's also not going to get into little nuances like how Christmas is usually a romantic holiday where he comes from, despite knowing Hermes would see that as an opportunity for massive hype.]