How can she put forth her best efforts when no matter how carefully she works, the item will still be defective? If no one cares, why should she? In contrast, when defects are rare or nonexistent or well explained, she understands that the management are accepting their proper responsibility, and she feels an obligation to put forth her best efforts: they are now effective.
The supposition is prevalent the world over that there would be no problems in production or service if only our production workers would do their jobs in the way that they were taught. Pleasant dreams. The workers are handicapped by the system, and the system belongs to the management.