mr_hippo, yes the driver of the car has left the junction open but that is simply common courteously, something I always do in a car is leave the junction open untill there's space to get clear of the junction in my lane, what a stationary cat does not mean is that it's safe to turn right through the junction. Especially when you're turning right you wait until you have a clear view of the road then move through the junction. You certainly shouldn't just go through a junction unsighted because the car in front has decided to go.
I'm thinking of an incident where a friend of mine was in a collision, when driving a car, in similar circumstances. Someone turning right went through the junction, that was close enough & she was braking hard, but the car behind blindly followed through the first car. My friend having used up most of the available traction couldn't stop in time and the cars collided with each other, though this was at very low speed.