They say that God, Jesus, or Mary can appear to someone. Who are these people who get to see Jesus or Mary appear to them?
Are they people who need to have Jesus or Mary appear to them? For example, God allows them to appear to the person because if they don't see Jesus or Mary they could fall away from the faith.
Or do you think that it happens as a 'present' for the people who are on the same page with God? Someone who will be faithful no matter what... will they get the pleasure of seeing Jesus or Mary before they die?