Disclaimer: I have never used Uber.

What if user orders Uber from one city to another? If driver is then in another city, wouldn't be nice to give him some rides in that city or when someone wants to go back to original city? What about cities that are near the border? If user would like to go shopping to another country? (Not uncommon in Europe. Long time ago I used to take local bus from Poland to Germany, do some shopping and go back)