If your customers or consumers have invoices that are well overdue, then you're effectively lending them cash. They signed a contract with you when they bought your products or services, and that expounded that they might pay inside a certain period of you supplying them with a valid invoice. You kept your end of the bargain by providing the products and services, and providing the valid invoice. If they do not pay you on time, they're effectively making an attempt to borrow money from you.