I hate to seem like a conspiracy theorist but I think one of the main reasons for a push to digital licenses on iPhones is so T.S.A. agents can say something like, "If you can't afford an iPhone than how can you afford a plane ticket? That seems suspicious..."
I can't drive but I have an amateur radio license Extra class. Ever since 2015 the F.C.C. has had "paperless" licenses for amateur radio operators and anyone who wants a hardcopy can request a printed license. I got my paper license in 2014 before the policy and it's good for ten years. When I renew my amateur radio license in 2024 I'll request another printed license.