What about for roundabouts where, depending on the direction you are coming from, the lane priority changes?
e.g. this junction: OpenStreetMap
There are specifically no markings on some of the lanes on the “roundabout”, but there are on the slip roads leading up to, and away from it.
e.g. one of the slip-roads leading from the dual carriageway, both lane 1 and 2 are “ahead” lanes and assume you will stay on the roundabout, with lane 3 being a right turn. you could turn left and rejoin the dual carriageway from lane 1, but it isn’t required.
However, people on the roundabout waiting to join the dual carriageway in the same area, lane 1 you MUST join the dual carriageway, lane 2 is an optional ahead (staying on the roundabout) or left to join the main road, and lane 3 takes you into town… with the option to rejoin the dual carriageway in the opposite direction.
To me, this is not a roundabout. Lane priorities change depending on the phase of the lights, and where you have come from. I don’t know of any non-controlled roundabouts that do this.
Specifically this roundabout, if you “mess up” and end up missing your exit, it becomes very confusing which lane you should be in to fix your mistake, unlike a roundabout where you would move right, and stay there until you got back to where you were originally.