YOU are leaving out something important. Increased productivity is not simply the result of employees working harder. Increased efficiency is the result of processes being improved that assist the employee by streamlining their workload. One small example was (finally) the addition of address barcodes, eliminating typing and the time it took, ntm errors eliminated. Residential release was a major productivity improvement. These changes depend upon management/engineers, not couriers.
I think you are placing the blame on the wrong group.