Not 100% sure in the case of Singapore, but the double yellow lines indicate no stopping.
For places where we are allowed to park on the sides of the roads, there are either lot spaces already allocated and drawn out, or there will be no lines painted on the road.
Double yellow lines in the picture here indicates no stopping at all times, so it would be a little pointless to have the curb indicate no parking again.
The curb might just be for visibility, can’t confirm.
Sounds like you’re pretty fanatically rooted in your belief and we’re all slightly different from you 😂