It was caused by the woman not being intelligent about the property she took possession of. She took it knowing it was too heavy and walked away knowing it was too heavy and walked out of the store knowing it was too heavy. At any point along that path she could have stopped at any of the registers with bags and changed the outcome.
She chose to take a risk. With, ultimately, fatal consequences, whether as a direct result of the cut or poor hygiene on her own part or at the hospital where she was treated.
She knew it was improperly packaged but the paid associate did not?