Why don't the US Mission know people when it chooses to recruit people?

Because it is easy to cause shielding risk. If the leader of Meituan's preferred site is a good friend or relative of the employee, then the new employee may receive special treatment and the workload will be reduced, which is unfair to other employees and will also reduce the enthusiasm of Meituan's preferred workstation. Meituan is more inclined to recruit and give up some people with internal relations, mainly for fairness and better safeguarding the principle of fair competition.