Q. Why is ingress data free with Azure?
A. Most cloud vendors only charge for egress (outbound) data and not ingress (inbound). There are numerous reasons for this. Primarily it removes barriers for customers to move data into the cloud which then encourages applications to be placed in the cloud service to use the data and of course encourages even more data to be placed. Azure charges for data storage and the services running in Azure using that data. This is known as "data gravity", the services follow the data. Additionally most customer data is egress, for example a request is made to a site which is very small but the returned data is much larger.