It is very hard for new people in town to meet
other people. Old friends tend to associate with old friends because
trust takes time to develop, new acquaintances are always difficult to
assimilate into a friendship network.
As a consequence new people in town find it easiest to meet other new people.
In San Francisco, restaurant servers are often the new people in town and the interesting people too. Chain restaurants and new restaurants are the places where server turn-over is high and where new people eating out can meet other new people.