In the 1960S and 70s, fabric was inexpensive. Most cities had several budget fabric shops. Many people owned sewing machines. Stores offered sewing lessons and girls learned sewing basics at school in home economics classes.
As clothing became more creative with the new bohemian and hippie fashions, a girl could take a basic sewing pattern and add details like embroidery, interesting edging, or the use of nontraditional fabrics. For instance, you could use fabric usually reserved for curtains to make a long vest, use upholstery fabric to make a coat. For a while, girls tore up the legs of old jeans, added pieces of other fabric or another set of torn-up jeans to make a skirt
One fun project for me was to make a pattern for a long dress and shorten it. I made the collar a Nehru style but used a different fabric than recommended, an Eastern European pattern. I also used the Eastern European type pattern for a wide belt and edged hem. The final outfit did not look much like the picture on the pattern. It was fun!