@endo54: I can see a few possibilities.
1. The requirement is specific to Haare, being in the King's City, because the staffs here are essentially the Kingdom's emergency army, running the guild normally until something serious show up then they get sent out to deal with it.
2.That receptionist alone is the OP one, the rest are more 'normal' in term of standards.
Either way I get a feeling the parents simply misunderstood the goal Nanari has (to be that ever smiling, cordial receptionist) as something grander, and so they sent her to the school where nobles and royalties attend.
Basically I'm expecting a lot of Unreliable Narrator and a whole slew of misunderstanding comedy.