You think too much. (The left indicator goes on, off, on, off. The picture shows the noment the indicator was off )

In the book it says the driver is allowed to overtake from the right when the driver on the left wants to turn left and gives clear indication. Here by indication I assumed he would turn his left indicator ON. But in the picture that was not shown, so in real life situation is it ok to overtake someone who looks to be turning left but have not turn on their indicator.