It's not quite true that almost all countries have household registration systems. Many countries, especially in East Asia like China and Japan, or parts of Europe like Germany, do have such systems, often tying family records to services. However, English-speaking countries like the US and UK typically use individual-based records instead. Estimates suggest maybe 50-100 out of 195 countries have household systems, so it’s common but not nearly universal. China's hukou is also more restrictive than most, which makes it stand out.
My top Grey's Anatomy characters of all time as of Season 10
1. Preston Burke
2. Derek Shepherd
3. Denny Duquette
4. Mark Sloan
5. Addison Montgomery
6. Christina Yang
7. Richard Webber
8. Alex Karev
9. Izzie Stevens
10. Owen Hunt
HM: Miranda Bailey BEFORE she has Tucker