Synthetic or Artificial food coloring were originally manufactured from coal tar, which comes from coal. Early critics of artificial food colorings were quick to point this out. Today, most synthetic food dyes are derived from petroleum, or crude oil. Some critics will argue that eating oil is no better than eating coal. But the final products are rigorously tested to make sure they contain no traces of the original petroleum.
A big reason to go artificial is cost. Synthetic dyes can be mass-produced at a fraction of the cost of gathering and processing the materials used to make natural colorings.
Another reason is shelf life. Artificial dyes might be longer-lasting than natural ones of the same color. Also, although nature produces an impressive hue of colors, those suitable for use as a food dye are limited. But there is no limit to the variety of colors that can be artificially produced in a lab.