There is often no bilateral recognition of Medical Degrees with other 1st world countries. The NUS Medical Degree does not get you registration or emigration points for a Singaporean.

A foreign Medical Degree (OZ/NZ) is registrable in Singapore and it also earns emigration points to get work or PR status in OZ/NZ.

Medical Doctors earn higher salaries in OZ/NZ than in Singapore not to mention a lower cost of living with regards to houses/cars (the 2 big ticket items)

Only on selected universities in OZ/NZ not all medical degrees are recognized in Singapore. But if you can stay overseas and enjoy better quality of life, why would you return to sinkieland? Ministar's children perhaps?