Many nations in Asia (like Korea, taiwan, and japan) are worse. A Taiwanese friend of mine told me people in Mainland China (white collar) work less hours than Taiwanese! haha
A lot of it is about "face" everyone is trying to show off for the boss...some of it is about profit margins. Not sure about Singapore, but the export OEM industry in Taiwan has a VERY Very low profit margin and since these are family owned businesses, mostly, they treat the workers like serfs or slaves, and work them 10-12 hours a day, instead of hiring more staff. THEY OFTEN REALLY ARE WORKING, not setting their trying to look busy until the boss leaves, as I witnessed first hand in Japan.
How it Singapore's environment in comparison? Does it differ a lot when working for a local company as compared to a big multinational?
It's so funny how Germans or even French can work less and still have very high productivity ratings. The average French now (by law) works 37.5 hour a week, but from first hand experience working with French offices when i lived in Switzerland, you will rarely find a French person in the office in the early mornings or afternoons. Same is true in Italy (maybe more true), especially as it gets later in the week.
However the productivity rate is higher than America or Japan.
How is that? Maybe working smart and not trying to show off for "face"is more important???
Good luck trying to convince so folks of that, as they are not used to managing by productivity.
This is even more shocking when you find out these managers got their degrees in a Western nation.

"The reasonable man adapts himself to the world; the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man."
-George Bernard Shaw