[brchr]

I have always found selfish routing to have interesting implications for a world in which traffic is more coordinated and centrally managed -- be it through present-day apps like Google Maps and Waze, or some near-future technology with autonomous cars communicating with one another. The happy Roughgarden/Tardos result that selfish routing is only 4/3 as bad as coordination is great, but it also means there’s not much slack to be picked up: fully coordinated routes would only be 3/4 as long as the status quo.

(Of course that's not the entire story on autonomous cars, for instance, because they will also get into fewer accidents, react to changing traffic conditions faster, can potentially drive more tightly at high speed, etc.)

Anyone interested in selfish routing should check out Braess's paradox, which is wonderfully unintuitive and strange:

https://en.wikipedia.org/wiki/Braess's_paradox