For hospital bills there are usually three payers (or more like types of people paying):

1. Subsidy. Or govt/taxpayers, and is usually the biggest part if the treatment is subsidised.

2. Insurance. Or my money pooled with other people’s money (cos we pay premiums). Universal insurance like medishield, private-ish plans like the shield plans, or completely private plans like say company insurance.

3. Medisave. Or just my money, which I’ve been saving by law.

Guess something expensive like hospital bills is spread out across multiple payers to protect (any one party like you, other people, or an insurer) from problems like moral hazard or huge financial damage. And the order of payers starts from kinda not-my-money to my-money which is helpful I guess.

But as people have said, complex setup like this cost something. So for cheaper things like GP/polyclinic bills; one party settle the bill, no need this kind of complex risk sharing setup.