[mikepurvis]

I believe Google Maps adds a bit of a rng in which route it will recommend when two otherwise similar in distance/time. Obviously the traffic input also affects this, but that's a slower feedback mechanism; better to distribute the cars all leaving the airport for downtown across the 2-3 possible routes upfront rather than dumping them all onto route A until it's a jam and then all onto route B until it's a jam, etc.

[psunavy03]

I'm sure Google Maps has had to put their thumb on the scale in numerous instances. I recall reading articles about it "discovering" more optimal routes between Point A and Point B only to find things like the new "optimal" route being down a neighborhood street, and then the locals started squawking.

[bigiain]

Annealing.