I agree with you and wish we were like Denmark but I also agree with
@Pale Rider insofar as a UK jury or judge would not consider this "far below" competence enough to qualify as "dangerous" in law, which is a disgrace and damning indictment of how pathetic UK driving standards and laws are.
To me, it doesn't really look like the driver took any notice of the cycles at all. He was in his lane, they were in their lane. He hasn't taken notice because of the lanes, and I am guessing he is also distracted, chatting to his colleague, almost misses his turn, so brakes late and turns in, without using his mirror or thinking.
Looking at the definitions of careless vs dangerous the distinction seems to be one of intention. So if you are deliberately dangerously overtaking, or deliberately driving a defective car, or deliberately driving after taking drugs or alcohol then that qualifies as "far below" the standard of a careful and competent driver. On the other hand, without an intention to cause a problem, it seems to get classified as "careless".
@mjr says that he wishes we were like Denmark.
@steveindenmark says it would be a ban and a retest. Well, that's also what can be imposed in the UK for both careless and dangerous driving, so I don't understand the distinction. The key difference between the two offences is that dangerous driving can carry a prison sentence and a larger fine.
The weakness it seems to me is that the offences only look at the behaviour of the driver and don't really take into account the seriousness of the result of their actions. Hence I have always thought that there should be a reparations element to the sentence, perhaps in liaison with the victim (mediated of course). For example if, when turning left he had hit a car, the chances of injury are very slim. It's the same action though. For the cyclist the consequences could have been much more severe. Luckily he landed clear of the vehicle and any other vehicles and his helmet prevented his head whacking the ground.
Maybe a compulsory cycle safety course where the driver has to go around on a bike for a day (or on some sort of tandem if not a cyclist) with a supervisor so they get a much better understanding of how their driving affects cyclists, along with reparations to the victim...