At least a couple of years ago at ORD T1, it could be quite the frustrating experience to try to find any UA check-in agent landside (at ORD T1) at around 9pm (or even a bit before) at times. It seemed like checking in “premium” passengers or assisting with IRROPS was something UA couldn’t care less about even if it tried. Never had comparable experiences with DL at DL hubs. Even AA@ORD was better at the time than UA.