Logistics

With the population of the planet nearing eight billion people, Santa’s resources were pushed to their limits.
He had given up paper maps long ago, and now relied on a navigation computer with every delivery coded in.
Factors like the weather, visibility, cargo space, and proximity shaped his travels, and when the night was over, he downloaded his performance statistics for further refinement of the algorithms.
Eventually, he changed what it took to get on the naughty list.
Only the absolutely best people made the nice list.
And they were just too nice to expect gifts from Santa on Christmas.