Power BI developers automate business reporting by using Power Query to set up ETL processes that extract, transform, and load data on a scheduled basis. They design reusable data models and templates that can be adapted for different reporting needs. Scheduled data refreshes and automated alerts enable real-time updates and notifications, reducing the need for manual data entry and report generation. They also create dynamic measures and calculations using DAX, allowing reports to automatically update with the latest data. This automation significantly reduces the time and effort required for regular reporting tasks, enabling faster decision-making.