Comment by anigbrowl

you're allocated a "Household" (Hukou) and you aren't allowed to leave.

This is really not accurate. Historically people have been disincentivized to leave by being excluded from social services and so on, the intent being to avoid large cities turn into mega slums. But the Chinese state has begun to dismantle the hukou system in recent years and allow people to move to mid-tier cities without restrictions, and to grant hukou rights based on duration of residency.