Useless functionality use Delta!

App is useless. It knows i have a reservation for today, booked together w/ another traveler,for which I am checked in but does not recognize there IS a mobile boarding pass for the flight.
The "check in" feature requires me to type my name & confirmation #, even though under Reservations it contains my flight info. Why do I have to retype this? & Why if I am already checked in (from another device) does it not register this and simply show my boarding pass?
The Delta app does NOT have these problems.
Under Notifications: why do I have to opt in to receive them for each flight individually? Of COURSE I want to know if its beed delayed, which it has btw.
Booking on the Delta app, also far easier, but Ive gone on long enough.

Kekinnyc about United Airlines