Hard to believe, but the staff/gate agents have actually improved over the years. In the past, many of them were downright hostile. They still need to improve. A first step would be not to show how exhausted and tired they are, as it can come off as if you are annoying/distrubing them when asking a question.

This is something completely within Delta's control to fix, both through customer service training, as well as increased staffing (if that's required). The check-in staff at the Skyclub were bad for years, but they made improvements and now they are fairly good. Same can be done in the gate areas.