Datal Seniority means that you cannot vote with your feet. The employer knows that they can jerk you around because you wont leave because either you are close to a command, get all your rosters that you want or will go onto the 'WonderJet Mk. IV(-ER )'very soon. Your employer knows this and this facet has become part of the IR landscape with respect to their negotiation strategy for quite some time
A very wise observation Anthill. If only our unions would see this too...
PG