most of the customers of SIA are:
a) foreigners flying into Singapore. Its the rule of the airlines...the fares always cost more expensive flying out of the carrier's home country, where they are the major player. So Singapore-India-Singapore is always cheaper than India-Singapore-India on SIA. Applies for all airlines.
This is caused by the protected nature of the industry.
b) flying on company's account. For duty travel, most companies use SIA. If you are the employee of the company, why would u not fly SIA?
I doubt SIA will fall into the re-hiring act to be in force. They are already long time out of it. Already their retirement age don't apply to the stewardess...unlike flying aunties that you see on other airlines, you won't see many of them in blue kebayas...only a handful in red, rarely in brown.
Of the unions in SIA, the pilot union is the strongest and the rest of the unions look to them for their Collective Agreements. Really its the training that goes into making a pilot that makes their pay so high. Nowadays one can land a A380 on autopilot if one chooses to.
In a certain sense, a pilot is no different to a MRT train driver. The only difference is that, if there is an accident, the stakes are higher - more high value passengers in first and business class and in the air, something happens, chances of survival is slim.
Other than that, there are no strong reasons. I think the management recognise this, and not for the first time, they always throw in new things during the CA negotiations. From scrapping allocated first class seats for non-flying pilots to reduced allowance...
Actually the incentive for the pilots to switch is high but not many actually do it. I heard alot once wanted to go over to Middle East as Emirates is expanding - but the overall package is not big enough. Yes, these airlines (China and Middle East - these are the only airlines hiring actually) pay higher, but other factors - eg: exchange rate of the US dollar, etc makes it not so attractive.
LKY once said, Singapore don't need an airline, he can practically come in and sack the entire lot of pilots and start a new airline. Lets see if the latest spat ends up with a visit to Istana.