Several reasons. Rubber mulch is a premium product that will last you 10 years with little yearly maintenance compared to wood mulch. Rubber mulch will not rot, decompose, and since our product is about 5x heavier than traditional mulches, it is less likely to blow or wash away. Typical maintenance can include a yearly top-off, raking heavy traffic areas, and sweeping sidewalks or pathways. It does not harbor pests and decreases weeds. Rubber mulch is a green product!