This is a difficult story to write, because I do not want anyone to come away making sweeping generalizations based on it.
I was in a Berber village in rural Morocco, up in the Atlas Mountains. To construct buildings, people would ideally make bricks using cement, sand/soil and gravel. Cement, in practice, was expensive and in short supply, and the last time a bag of cement was obtained for the construction of a public good, a classroom, portions were siphoned away until so little cement remained for the bricks that the room ultimately collapsed. Building public goods like roads and schools was a task assigned to teams of local men, in rotation.
Now a new classroom was being built, and I saw the bricks being made. The crew it fell to had brought out wheelbarrows, shovels, and two old, metal molds – boxes with two sides cut out. The molds were of the same size but had different sides cut out, giving them a slightly different appearance.
A lot of concrete had been mixed and was waiting to be shovelled into the molds. However, only one mold was being used, causing a bottle-neck. I inquired why.
The villagers were unaware that their two molds – that they had been using for construction for as long as anyone could remember – were the same size.
When I think of productivity gains, sometimes I remember this story.