John controls when and how he interacts with retailers on his mobile device through a standardized "shop mode" switch, which was developed as part of a set of "Consumer Engagement Principles" or guidelines established by the consumer goods and retail industry. The principles were created in response to growing consumer concerns over digital data privacy and a lack of control over how companies collect and use personal information. They aim to build trust with consumers by ensuring mutual value for consumers, businesses, and society through responsible data practices and a balanced exchange of value.