Absolutely nothing to do with 'union manipulation', indeed MrSurrey, if you knew anything of SIA you would know that union manipulation of the management is simply not possible.
In this instance SIA offered the B777 rate to the A380 crews, less than the 744 rate, yet SIA has always accepted that the larger the aircraft the larger the dollars. The union were unable to reach an agreement with SIA and sought arbitration and won, that, in itself, in Singapore speaks volumes!
If the free market rates were applied to pilots salaries we would never be on the same rate of pay two years running! You are not a pilot, are you, MrSurrey? I can't think of any profession that would accept the instability of ever fluctuating pay scales, there is almost always a base rate to work from.