At a meeting of the Progressive Christian Network of Victoria after the speaker had spoken about God intervening in her life Lorraine Parkinson questioned her about this and said that some help had come from God "when called upon".
This was significant.
It was consistent with my adult experience that nothing happened until I called upon God in my distress.
Then there was an answer.
This, however, does not apply to my childhood experience of seeing God in a vision. My three year old self had not called upon God.
But this is consistent with the idea that it is God who instigates contact.
"We love because he first loved us." 1 John 4:19 (NRSV)
People who experience a hint or nudge in a particular direction, perhaps a warning, may already be in relationship with God and this could explain why some are warned and others are not.
It seems to me that this happens in order for it to be clear that it is God who is responding to their call for help, and this in order for them to come into relationship with God.
This is my experience.
[Scripture quotations (marked NRSV) are taken from the New Revised Standard Version Bible, copyright 1989 by the Division of Christian Education of the National Council of the Churches of Christ in the U.S.A., and are used by permission. All rights reserved.]