Laundry baskets have holes in them to promote better airflow to your clothes. Even when taken fresh out of the dryer, clothes can have trace amounts of moisture in them, and the holes provide ventilation to reduce any possible mold and mildew. It’s a design idea that likely started from more traditional woven baskets and influenced the way plastic baskets were made. In addition, the holes make the baskets more lightweight, so you can pile them up with clothes and carry them with ease.