When I was growing up in the 1950s, my father sold and repaired sewing machines for the Singer Sewing Machine Company. That logo was on the side of the gray panel truck he drove. For about a century, women used sewing machines at home to make and alter clothes for themselves and their families. Presumably that meant people made a living selling and repairing sewing machines for at least a century.
My father worked out of the Singer Store in the prime retail area of South Main Street in our town of Greensburg, PA. He became an assistant manager there, then manager for smaller stores in the area before becoming the Greensburg manager. He was the first manager at the new store when it relocated to Greengate Mall. But the store didn't last long. By the mid 60s, home sewing machine sales were falling. All the Singer stores soon closed. They had also begun selling vacuum cleaners in the 50s, and later my father got into that business, becoming the factory rep for Hoover, until he retired.
His father had been a coal miner until he contracted Black Lung and retired on disability. He had two younger brothers: one a truck driver, the other worked in a factory in the 50s and 60s. A man's job was supposed to support his family, and thanks to union contracts, many factory jobs did. My father's income was usually near the margin. He was paid a salary but he depended on commissions on the sewing machines and so on he sold. We had a new house in a new neighborhood, but supporting that and three kids was a struggle. Before I was in high school my mother had to get a job. She eventually worked her way up to be a hospital administrator, and judging from the people who worked for her, a good one.
So selling and repairing sewing machines was apparently not a great living. But at least it wasn't coal mining. Now it's a job that almost nobody has anymore. Nobody drives a panel truck with that big red S on the side. My father's occupation disappeared before he was 50. Everything he had learned about sewing machines was pretty useless.