A Chap I flew with in the late seventies had done quite a while as a baggage handler whilst paying for his flying training. Then as now, theft was rife. His advice was that the only way to make it even moderately difficult for the bad guys was a broad strap, KNOTTED. The reason was that the guys only have a few seconds to get in and out and resecure the bag. No time to undo and retie knots, and cutting the strap is too immediately obvious to the receiving pax, which points the finger at that particular handling crew
And for those of you who like the knotted strap or cord solution, here's a little extra and easily applied security check from the days of sail:
Thief knot - Wikipedia, the free encyclopedia
Jack