Flipping heck though - hearing a scream and not checking on it, hope I never do that.
It may not be as simple as somebody just ignoring a scream. In my house there's about 5-6 houses nearby where I would be able to hear a scream from and it would be impossible to determine which direction the noise came from. That's before considering it could have been somebody in a street or back garden. If I didn't see something obvious I wouldn't know where to start with trying to investigate a noise I'd heard.
Of course, when the police turn up to say a neighbor has gone missing and ask if I'd heard or seen anything unusual, it's easy to then put 2 + 2 together and work out where the scream likely originated from.