I've received reports that some major Open Tour Bus companies servicing Mui Ne have told their customers that they can not sit with their valuables--that they must put them under the bus--then later parters of the bus attendants are going through their bags and robbing passengers. Likewise I've recently heard about customers falling asleep on the bus and getting robbed.
Never, under an circumstance, put your valuables(electronics, money, etc.) in the compartments under the bus. Any attendant that instructs you to do so is saying this with the sole intent of robbing you. This has never been standard practice in any company. Likewise, keep track of your valuables at all time. Don't fall asleep with valuables out of your reach.
In an unrelated matter, I've received report of another theft which was reported to local police, but the police refused to file a report out of sheer laziness-despite the fact that the victim had accurately collected the names, passport number, hotel and even flight information of the criminal! More information on this exceptional case soon...
The point being, if you do happen to get robbed, unfortunately you are on your own. The local police will not help you.