Hukou is what I was referring to. It's not just welfare, but distribution of state money (like USAs census) and in some places required to purchase property in that area. Most ignore the requirement (like they do many rules), so I understand why you say they "don't need to register", but technically it is required. This is where it gets fuzzy when you say something in China is "required" - technically it might be so but in practice it's not enforced, unless the government has a particular reason to enforce it, and even then it's usually temporary. It ends up being a weird situation where technically there's more restrictions in China but in practice there's a lot less red tape to deal with than living in the US. What that means in practice is if Beijing doesn't like you, they will find a laundry list of requirements you violated. Bringing it back to AirBnB IPO that concerns me.