In countries where most/all of the cards issued in that country are chipped cards, some badly-informed merchants or store clerks just flat-out refuse to accept non-chipped cards. I have only ever had it happen to me once (at a Tesco), but I have had to explain the process of swiping a card any number of times in France. I've also read elsewhere that Nederlanse Spoorwegen (Dutch railway) rejects non-chipped cards as a matter of policy, but then again most of their stations don't accept any MasterCard or Visa cards, so it could just have been that.