It should be noted that the reason there isn't a FA union at Delta is that - for the most part - Delta has treated it's employees well enough that they didn't want to be bothered with a union and it's associated hassles and expenses. Back in the 1980s, the employees actually got together and donated enough money to pay for one of Delta's new 767s (subsequently named "The Spirit of Delta"). While today's Delta is far removed from the Delta that existed in the 1980s, there is still considerable company spirit, especially among the legacy Delta people (my understanding is that most of the push for a union is from people who used to be part of Northwest - not the legacy Delta - who were used to being shafted by their employeer).
There are some pretty obvious distortions in the published stories currently out there (the $250k salary for a FA is obviously fiction). Hopefully time will give us a better idea of the truth of the matter.