How can the cops take so long to get there?

Seriously, what's the point of the cops? The first part at the beginning when the guy is in the house and the girl is hiding under the bed, Halle Berry must have been on the call to her for a good while and yet the cops STILL don't turn up? Then when they are trying to track the car with the paint and everything, okay they had no exact location but they knew the freeway they were traveling on, and yet the cops seem to take hours to catch up with them. Would it really take this long for cops to be on at the scene? There must be some sort of unit or squad car available that would have caught up to them.

If the cops really take this long to be at the scene, then surely Alex Jones was right and you need to have your gun cocked and ready to use on any intruder. Don't be relying on the cops who seem to take their sweet time?