Originally Posted by
USA_flyer
Also a good reason to have a return ticket is to provide evidence that you plan to leave!
Indeed, it can be useful for those trying to use the US VWP to travel to the US, or for those traveling to the EU as a tourist with non-EU/non-Schengen countries' passports. But neither the EU/Schengen authorities nor US authorities would care about me providing evidence of a plan to leave.