I share Ujang's concern that ID-ing the people is a tricky thing. It is a matter of political, feasibility, as well as ethical concerns. I don't know much about international ethics of statitistics or Indonesian law on statistics. Ujang's account is then very helpful to me.
Come to think of it, the administrative-purpose rationale is in fact what I had in mind. A single ID number would likely to help cut a lot of inefficiency. And it should be able to lend itself as the basis for targeting a public policy. This is where ethical concern amplifies. We don't want a Big Brother watching everything we do. But we want to have administrative procedures efficient. The solution should lie within the two objectives: there's a tradeoff. And that cries for a careful rule of conduct.