For a number of reasons
Lembrado
1. Unlike some who came from
Big
Airways on a pension and are happy to work for pocket money, I don't have a 757/767 rating.
2. The company won't put 737 pilots on type rating courses because they cant spare them off the 737. This of course runs contrary to what I was told at interview.
Unless of course you happen to fly the 737 (very badly) at STN and do a deal with the little man mentioned earlier ! 
3. I like my life in Scotland, I like my days off at home, not 7000miles away in a third rate hotel in India. We are s'posed to be Scotland's airline so why do all the 757/767 guys spend their lives living in hotels? It suits some it doesn't suit everyone and the guys who cant stand it anymore are leaving.
Homer_J
If you are 737 or 757/767 rated check out Wynnwith,Storm or Zenon because contractors get a better package.