In general, we know a lot the orbits of asteroids, however, that is not to say we can track them in side a 1 km control box like we did with some LEO satellites, meaning that we know the position of that asteroid within a 1 km cubical box.

Eros is just one asteroid. There are millions of others. As I said, comparing to comets, asteroids' orbits are relatively stable. But it doesn't mean that once the asteroid's orbit being determined, it will never change. Constant observation and tracking is required.