The reason why DL is able to provide more locations to its rampers and bring more work back from regional carriers to DL mainline is because DL is running a more profitable business which means they can pay a premium to keep their people happy.
UAL stock is in a hefty retreat today after UA informed the SEC and investors that its 3rd quarter revenue will be weaker than expected driven by int'l routes, including China.
"Three years after the 2010 merger between United and Continental, analysts and investors remain uncertain about the combination's success. In a July report, JPMorgan analyst Jamie Baker noted that the second quarter of 2013 represented the ninth consecutive quarter of earnings declines for the carrier.
"Wolfe Research analyst Hunter Keay also reduced estimates and said he continues to view Delta (DAL_) more favorably.
"We continue to hold a skeptical view that United's margins (and stock price) should converge to Delta's within the investable future," he wrote on Friday. "We have yet to see a data-driven argument as to why this convergence should occur."
http://www.thestreet.com/story/12051529/1/united-airlines-disappoints-once-again-and-shares-fall.html
The major reason why WN people make as well as they do and why DL employees have gained as much as they have over the past several years is because DL is running a strong and profitable business.
Unions can only negotiate what a company is capable of paying.