The reindeers are mostly for the show. Everyone in Northern Europe knows Santa lives in Korvatunturi
in Finnish Lapland, not in the North Pole or Greenland as many think. Official police reindeers are there to show how these animals, as well as Santa, belong there
BTW, remember this next Christmas: if your kids write a letter to Santa and post it latest end of November, they will get a personal answer from Santa before Christmas. Address is:
FI-96930 Arctic Circle
Letters can be written in any major language, the answer will then be in same language. The service is maintained by the Santa's official postal services, Post of Finland, and paid by Finnish Tourism Board.