OK, somebody decided that the classic metal blade used on all plastic wrap boxes since the dawn of time cost too much, so they decreed that it be replaced with a plastic blade that costs essentially nothing:
Unfortunately, a thin plastic blade also bends easily and, after a few uses, cracks along the midline. After that, it simply doesn’t work; there’s no way to actually tear the plastic off the roll.
It turns out that a common hacksaw blade is exactly the right length and, oriented with the teeth pointing to the left, will rip through plastic wrap like, uh, a hacksaw through plastic:
That this hack should not be necessary goes without saying…
There’s a layer of double-stick foam tape between the box and blade. It’s probably removable, but I was in a hurry.