Those SIA girls are there to impress the Ang Mohs only. They don't give a fuck to local Sinkies.
This is the practice on most other airlines as well as they don't give a fuck to their locals. Once I was on a KLM flight from Amsterdam to Linate (Italy). When one of their local Dutch passenger asked for coffee and the flight stewardess was serving tea at that moment, she just rudely replied to that local passenger: I've only got 2 hands, you'll have to wait.