Originally Posted by
Xyzzy
UA could easily have made changes without affecting *A "uniformity" (such as it is). They c
uld have divided Y/B/M in a different fashion, say M for E+ and domestic PP fares -- and then only done instant upgrades from Y/B ... or some other combination, without getting rid of instant upgrades altogether.
DL used to offer instant upgrades on it's top two fare coach classes (Y/B), but they dropped that policy back in 2017. So I suspect this is at least partly due to UA deciding it no longer need to distinguish itself given that neither other legacy offers such upgrades.