I travel with two kids and all of their electronics, usually in coach, too often in the "short haul" car while on a long haul (because our destination station has a short platform they don't like to put us in the rear coach where they put most of the all the way through from Seattle to Los Angeles passengers). I try to convince them to at least cover things up on their seats but it doesn't always happen... we've gone to a meal in the dining car and come back to find the iPad sitting on top of a laptop, next to a Kindle. I scowl about it, but we've never had anything go missing.
We've heard, on some trips, of things like backpacks that have gone missing- I can remember one time where it was lost late at night, its owner having no idea where he might have last had it, and found the next day in a restroom of a different coach car than the passenger was riding in. One vaguely suspects that the passenger was not entirely sober, perhaps, though he also claimed that his laptop had been in the backpack and no longer was when it was recovered. I think the moral there might be, don't leave your laptop bag in a bathroom.