A successful on-demand laundry service like Laundr.io can benefit from an ETA notification system that alerts customers when their order is picked up or arriving. The system uses Python and Flask to trigger notifications, Twilio's REST client to send SMS messages, and a status callback to update the notification status of orders. The code demonstrates how to implement this system, including setting up the Twilio account, sending SMS notifications, and handling the status callback. This tutorial provides a simple way for developers to add an ETA notification service to their own applications.