As a rule of thumb, Private Payments fits any scenario where an XPUB might otherwise be shared or where sharing a static address creates a privacy risk.
Instead of posting a static Bitcon address, a party wishing to receive donations posts a Private Payments code. A donating party can anonymously pay a payment code using a unique address. As long as the donator engages in coin control, there can be no loss of privacy by means of chain analysis for either sender or recipient.
An employer may decide to enroll an employee's payment code into their payroll system, thereby guaranteeing that every payout gets a unique address. This way the employee does not have to share his addresses either monthly or through an XPUB.
Honor System Stand
The small-scale merchant who leaves goods for sale at an honor system stand could benefit from an alternative to posting a static Bitcoin address or running a server. A Private Payments code allows each customer to pay to a chain of unique addresses, thus enhancing privacy for the business.