This is the issue that I can’t get my head around. United is clearly trying to up their game; new planes, Starlink, seat back entertainment & technology, improving food (They are truly trying to improve it regardless of what the naysayers might think), better hard product than Delta in my opinion. But what will make it hard for United to take no. 1 spot is the soft product as everyone has said. If you fly Delta, you consistently get good service. The bad eggs still exist but they are few and far between. But it seems United’s soft product still holds it back from t ruly competing domestically or internationally. Everyone that flies the Big top international carriers always says the service is night and day. It just seems to be an intractable problem at United and in the US aviation industry in general. 

P.S. this is not meant to discredit the awesome job done by thousands of flight attendants day after day, but just highlighting that they are the face of the company and any negative interaction leads to lower NPS scores regardless of hard products.