This is a type of accident that is particular to countries that have bicycle lanes. Cities like for example Berlin have closed a large number of cycle lanes (where they are routed to the right of regular traffic) because of that reason, and replaced them with shared lanes.
That's a sensible policy. Here in Jakarta lanes are mostly for decorative purposes only, but the roads are shared by cars, trucks, autorickshaws, motorcycles, and various forms of human-powered cards (either pushed by a pedestrian or with a mechanism based on a bicycle). It is amazingly chaotic.
But one of the first things you learn is not only to be pedantic about signalling when turning but that you need to claim space because otherwise you are asking for an accident and if you are involved in one as a car driver, it doesn't matter whose fault it is: the motorcyclist/bicyclist loses on the physics and the car driver loses in front of the police (that's one way btw that police corruption protects the poor here).
The space-claiming is key. You do not want to be passed on the left while making a left-hand turn (they drive here the same side as in the UK). That has happened to me a couple of times and it is a major reason I do not listen to the radio while I am driving (with motorcylces that way at least I can hear them). Fortunately I haven't hit anyone yet (knocking on wood).
