Right up to the first runway incursion. Meet reality - paranoia's big brother.
Are you saying a professional crew would mistake a cactus vs a USAirways callsign? Are you speaking for you and/or your fellow pilots? If so, I defer to your judgement.
US has a reputation of avoiding such situations but I wonder if you are just slinging mud, hoping against reality, that something will stick.
Comparing US vs AWA that way will only result in your humiliation.