That's the problem with Singapore's employment laws.
For these kind of hourly wage jobs, there are typically two 'either-or' main attractions:
1) Flexible schedule, you can clock any number of hours you wish, and on any days you wish. Of course, weekend shifts should pay slightly more.
2) Pay correlates with hours clocked, so if you voluntarily 'piah' 50-60 hours per week, you can expect to get a handsome sum of money.
Now, what good is it to make it mandatory that the employees work insane hours (no flexibility) and on top of that, for an hourly pittance? That's the worst of both worlds.
Of course, it's good for the business owners and the rent collectors. But that's precisely what is wrong in Singapore: the govt has tilted the balance too much in favor of capital and had neglected labour. A successful business is a cooperation of capital and labour as equals, there's no reason to think that capital lords over labour.
No wonder productivity is low. No wonder the businesses are hooked on cheap foreign labour like a drug addict on crack.