For one thing, there are many different types of plastic. Think about a plastic juice bottle versus a sandwich bag. Recycling facilities must sort the plastic and recycle each kind separately, which is time-consuming and expensive. As a result, it’s often cheaper for communities to send plastic trash to landfills.
Also, many recycling facilities can’t process certain plastic items. For example, plastic wrap is too flimsy to be recycled, and grocery bags can get tangled up in the machinery.
Plus, plastic degrades each time it’s recycled. Glass and metals can be recycled over and over. But plastic can generally be recycled only once or twice. Making products from recycled plastic is also expensive, so most companies use new plastic instead.