Re: locks on luggage
Yes, if someone is determined to steal your luggage and/or contents, there is probably little you can do once they are out of your sight. Thus, locks or cable ties would not make a difference.
However, let's say someone was just randomly looking for an open suitcase (not necessarily intent on a certain suitcase). That thief would likely rummage through an unlocked bag rather than one that is locked. In many ways, this scenario is similar to locking one's car. If a thief wants YOUR car, there is little you can do to prevent its theft (alarms, steering wheel locks, etc. can be disabled by good thieves in seconds). However, if some joyrider is looking for a quick ride, he is more likely to try an unlocked car or one without an alarm/"anti-theft" device.