In some games especially huge open world games, fast travel is a necessity in order to save time. But some games don't have this feature and it will be a hindrance to travel from one place to another especially during missions and it will cause a disrupt in the flow of the mission and the player might not care anymore about the mission. The designer should make sure that if no fast travel is present in the game, the mission scope should atleast be limited to a particular area.
In Mafia 3, some objectives require only a few minutes to complete but these missions require Lincoln(the protagonist) to drive across New Bordeox(the place the game is played) from one end of the map to another in order to complete these objectives. To prevent this hassle, the designers must have used included a fast travel option or they must have made sure to prevent travelling such long distances on the map.
Far Cry 2
While it does offer the use of vehicles, there is no shortage of frustration from players about the speed of travel in Far Cry 2. The amount of time that it takes to get from one part of the map to the other, whether by running, car, or bus, can be taxing on the player who is just anxious to get to the point of play. This obstacle may create a sense of immersion for some but, overall, is more likely to foster a sense of annoyance and disconnect from the material in most.