"There is no moral justification for the government setting a retirement age, but they are able to. So it doesn't matter."
There is a minimum age to collect old age benefits from the government. The justification for that should be obvious.
The justification is to force people to work until they are too old to do so. Then steal whatever they have left with medical bills and price hikes on necessities.
Actually, the justification is to prevent old people from having to work. Retirement didn't really exist until the creation of pension systems in the late 19th century, and the modern social security system was a poverty alleviation measure introduced in the 1930s. Hell, social security was initially resented by older workers because of the cover it gave employers for firing them for being too old.
Social Security constitutionality was ruled on just months after the 'switch in time that saved 9' associated with a threatening to pack the courts and evade the checks and balances built into our "democracy." They ruled it was covered under 'general welfare' in a way that was totally historically inaccurate.
Furthermore, FDR and congress purposefully had it packaged in an omnibus style bill to evade democratic scrutiny over the individual portions, by purposefully torpedoing other aid to needy individuals if SS didn't pass, so that lawmakers wouldn't be able to vote on democratic view of SS but rather being damned in a catch-22 where they'd be accused of not helping out the needy in other ways.
Basically the whole thing was designed to not only evade democracy but also the constitution.
[] Recollections of the New Deal, by Thomas H. Eliot, pp. 102-115 (Northeastern University Press, Boston, 1991).
To make an overly dramatic analogy, if you were kidnapped and asked why the kidnapper was able to hold you against your will, the answer is because they've chained you up and they have the gun, and so on. That's literally the answer to why. The fact that what they're doing is morally wrong is completely irrelevant.
The government makes a moral justification of a savings plan but then when we dig down to it it's all ether and really just a scheme for bond rate arbitrage for the government.
The point isn't that might makes right is false, it's that the moral justification is a facade.
Edit: Although, when my time comes as it inevitably will, I think the wilderness would be a nice place to do it. Maybe in a tree.
The real question is why governments insist on euphemistic names ("forced savings") that imply the opposite of the reality of the programs. And why people put up with such financial repression schemes. The answer to the first question is to keep people from being too upset too suddenly, too many all at once. The answer to the latter is that the people usually don't get a say in these things.
For Singapore this program probably makes a great deal of sense since Singapore is singularly vulnerable given its location in the world. To build what they did they probably needed these sorts of policies. I suspect most Singaporeans don't mind all that much, though I don't know. We would very much mind this sort of thing here in the U.S. though!
As for why - the same reason why they get to decide what side of the road you drive on and what laws you follow. They rule the patch of land you were born on, and if you don't like it you can either participate in the system (assuming it's a democracy) or leave.