As others have mentioned [0], blockchains pay a lot for working in a trustless environment. The real issue is that there's not actually a lot of trustless environments that need such a solution. And there's better solutions in trusting environments.

To take your example, a country issuing identification numbers does not have a trust issue. The people generally trust the government to correctly issue and record an ID number.

[0] https://news.ycombinator.com/item?id=13420629