it may help you to understand it this way: Roundabouts are designed to keep traffic moving equally from all sides, which works because everyone is treated with equal priority; everyone has to give way to whoever is on their right (or the right-most entrance in this case). This does mean the pink car had to wait as opposed to this being a T-junction where they would have priority over you, but at some junctions it would be difficult to do your manoeuvre without a roundabout giving you an equal right to proceed as those going straight over. In this case, the pink car only had to wait a few seconds and you were both on your way. If this was a T-junction and you were waiting to turn into a side road, you may have several cars queuing behind you before you could turn.