White is the color of choice for many professions that are likely to be stained or dirty. Doctors, nurses, and for a very long time children often wear white. It's bleachable. It may show the dirt and stains more, but it can be aggressively cleaned to return it to white in ways that any other color cannot. Prior to modern chemical bleaching beginning in the early 19th century, it could be achieved by laying out a garment in the sun. You could use bleaching fields or your cut grass yard in the morning. Certain applied things could accelerate this, such as buttermilk, but it works on the oxygenation principle. This done after scrubbing the garment in boiling water with lye soap will keep it very clean in appearance.