Cope,, I feel your pain, BUT,,,,, I used to ship 50 lb boxes back when I had a print shop,, I would put one tape over the middle of the box, then three across the middle seam then one over each of the end seams and one one each over the top and side of the side seam. This would be duplicated on the bottom of the box,,, twelve years and I never lost a box of shirts to the box opening. I do the same now when I ship stuff,, I shipped a chainsaw lumbermill, complete with powerhead and two bars, one being almost 50 inches long to Costa Rica via UPS and it arrived without a dent. Load stabilization is a must. If the contents does not shift and the box is well taped it won't come open.
I have recieved many packages that looked like they had been packed by a minimum wage flunky who didn't give a **** about his job or the customer's goods,,,,,, uh, nevermind. PS,, they got to me,,, have not a clue how,,,