Okay, I’m going to actually take a shot at this.
Ghosts exist in a spiritual plane so they aren’t bound by physical limitations. You or I can’t zip across the country in seconds, but what’s time and distance to a ghost? When you’ve already made the crossing from the world of the dead to the world of the living, getting from New York to Los Angeles is trivial.
As for where ghosts appear, you shouldn’t assume they’re tied to a location. They can just as easily be tied to an event. So if they get murdered in a house, they might stay in that house. But they might follow the murderer instead. Or maybe the weapon used to kill them. Or the detective who’s investigating the crime.