Some people go missing because they are having a diva drama.
Some people go missing because of their own mental health issues.
Some people go missing because they have run into some trouble how ever small and can't face the consequences.
Some people go missing to escape horrific abuse.
Some people go missing because they are in fear of their life.
Some people don't realise they are missing they are just hopeless at keeping in touch/choose not to.
Some people change their name then die only known as their new name.
Some people die of natural causes and aren't found for a long time/ever.
Some take their own life.
Some are murdered.
Some are frauds either in their present life or the life and name and identity they were known by previously.
Some just want a fresh start - for their own reasons.
Some are taken by family i.e. arranged marriages overseas to a cousin or person they have never met.
Or was the case on this thread, a British family left Australia without saying they were returning to Britain because the wife didn't like the husband's family.
Or as in another example, a guy's family aided and abetted him disappearing out of his partner and child's life. Until the day came when he wanted to play, 'happy families' with his now 15 year old child. Err, that'll be a no.