"Virgin has to deal with unions too"
Yes of course they do, but the difference is that Virgin began from a lower $ base and the negs are all about trying to lift that to bridge the gap between them and the opposition. The problem is , Qf base has always been so much higher and now in order to be competitive they need to lower it- hence the conflict with the unions.
Also VA has had the benefit of most staff experiencing the growth of the airline from nothing and the pride ensuing from that. More likely then that the staff feel more connected to the challenges.
Having said that disenchantment certainly exists at VA too especially in the ground ops. They feel the pinch of not enough money every day.