Scaramanga
Brickhead
I think it's a relatively good play feature to have traders be autonomous and follow the most direct route, even if it's going around a city. There's no reason to stop in a city if its only going to slow the trader down. It's the city that's misplaced not the trader's sense of direction, or a trade route has to be made to the intermediate city first.I especially hate that you can know several turns in advance when, say, a barbarian camp spawns near or along a trade route and you won't be able to get a unit to protect your trader from going along that road, one turn/tile at a time, until inevitably they travel directly onto a tile already occupied by an enemy unit.
It's like watching lemmings walk off a cliff.
Running into unclear territory where barbarians could appear is part of the challenge of having good roads.