If nothing has been removed from the bag and contents show no signs of being tampered with the likelihood is that the padlocks have suffered 'trauma' somewhere in the handling process and parted company with the baggage quite innocently. Even the best designed automated baggage handling systems have gaps / joints / angles / turns / height changes which can and often do snag things like padlocks, straps and unstowed handles. You'd be amazed at the number of 'broken' bits the maintenance crews regularly remove from the baggage handling systems. At best most small padlocks on baggage offer only minimal protection if indeed any. The psychological benefits for the passenger (I've locked it therefore it must be secure and safe) far outweigh the actual pyhsical benefit gained from these 'toy' padlocks. Try busting one yourself and maybe you'll think twice about using one again.
Best use luggage with inbuilt (flush mounted) combination locks, you can now buy luggage which offers both combination and key operated flush mounted locks. Add a combination lock luggage strap for added peace of mind (making sure the lock mechanism fits snuggly against the case/bag) and finally if you really want to truss your luggage up like a Christmas Turkey then use cable ties.
The ultimate 'protection' is the shrink wrap service offered at some airports but you have to ask yourself 'why' and consider your Eco credentials when contemplating covering your luggage in swaiths of plastic.
Best thing to do is use your checked-in luggage to carry only clothes or items of little value and always carry your valuables in your carry on baggage.
Enjoy your next trip
