If I do something once then it's slightly annoying downloading the app from the app store, but I can live with it. It's not worse than opening browser and going to some URL.
United is a phisher’s dream target. No MFA possible, and they spam their customers with zillions of login links on dozens of different domains. I’ll bet you can register unitedcardawards.com and get thousands of credentials without even sending out phishing messages!