Originally Posted by
paperwastage
That's part of the purpose of the built-in lock.
If you use a standalone lock, someone can use the pen/zip trick, re-zip it back up and you wouldn't know
If you use the built-in lock, someone can still use the pen/zip trick but can't easily re-zip the bag due to the zipper handle locked. Of course, this is just a deterrence, and you run into OPs issue (actual zipper broke/cut open)
The OP should be glad they didn’t have one of those bling bling Rimowa’s with the built in locks. Or maybe it should be US DHS that is glad since it could end up paying up. Administrative searches that are permitted ought to be as minimally intrusive as required to perform the job — arguably, breaking someone’s bag and not finding any problem could be a sign of failing to be minimally intrusive.