The interesting question would be how many products came in lower, but sadly the article doesn't include that.

If 23% were higher and 23% were lower then you could make a reasonable argument that it's just incompetence from the store.

But if 23% are higher and none are lower, then that looks a lot more like malice - because the odds of you happening to have a 23% error rate than just happens to always work out in the retailer's favour are basically zero.