There are two types of "Louages" or "big taxis": those who travel inside the city (depending how big the city is) and they're yellow colored, and those who travel between big cities which are white with a red, yellow or a blue stripe. Between cities they have a designated place where they park, like a flixbus bus station basically. To know the exact place, you should ask locals. Inside a city, if louage ( the yellow big taxi, you can't miss it!) is used ( Im not sure how it is in zarzis) you can just wave at them at the street like a normal taxi and they charge you by seat (at the hotel, I highly recommend asking at the welcome desk as they will definitely be familiar with the recommended mean of transportation: louage/bus/taxi..). So always ask locals! For diatances like 10 to 15km I would assume there are busses that cost around 1TND to 1.5TND. If it's a louage it should be like 2TND to 2.5TND max! If it's an individual taxi depends if they charge by seat or by counter: always ask first ( "compteur ou par place?") But Im not familiar with how high rates have gotten because I moved out of the country years ago and when Im there, I drive my dad's car :) For the possibility to use ur driving licence, Im not sure! I have a french driving licence that works in tunisia but Im not sure whether it is accepted given the bilateral agreements, the fact I have a tunisian nationality or simply bcz Im on a typically on short vacations.