> I'm confused by that move - why make it free when they could easily charge their captive audience for it?

My understanding is that it's actually a condition of using Starlink for commercial aviation. Every other airline that's announcing a partnership with Starlink is also providing it for free to customers.

IMO, it's a way for Starlink to put pressure on other satellite internet providers. The utilization of free wifi will be way higher than paid wifi. And the other networks - be it OneWeb, Viasat, Hughesnet, etc. don't have as much available bandwidth.