I think a lot of people don't realize that the airline is not the sole party involved in setting the price of WiFi. It also depends on the deals that the airlines negotiate with the internet provider(s) used on various equipment types. Because WiFi was added piecemeal to aircraft over the past decade, there are a number of different technologies and providers involved. Gogo, Viasat, and Panasonic are the providers that AA uses, and each of them has a separate arrangement, separate privacy policy, etc.

Also, to be clear, Delta's new free offering is only on narrowbody domestic equiment. NOT regional aircraft and NOT widebody aircraft, because those equipment types use different Internet providers that have not yet negotiated with DL to offer the customer-facing product for free. Apparently it will take another year for the full DL fleet to offer free WiFi.