Yabvu
As a biker myself (swmbo is also a rider) we have a lot more to deal with than cars.
You say about bikes filtering and then cutting in, we aren't cutting in, we just have a much larger space awareness about where we fit due to not having a metal box round us.
Filtering through traffic is also in the Highway Code, it's called 'making progress' and we are taught this when learning to ride.
It also says in the Highway Code, and during driving lessons, that you should check your mirrors before manoeuvres, such as lane changing, changing speed, opening doors etc... . If this was done then there wouldn't be a problem as you would be aware of the motorbike in the first place.
I agree with those pp who have said that drivers should have to take their cbt as part of driver training. After my cbt I found my awareness on the road was much greater and I was doing a lot more checks around me.
As bikers we are constantly looking at what is going on around us, we are looking at the road ahead, the traffic, what cars at junctions are doing. We do this to survive.
I think you need to look at motorcycle safety videos and see what we contend with day in day out from idiot drivers who dont know the laws. I would say there are more idiot I'll informed drivers than there are bad bikers, but that's from experience.
Oh and I drive a car and a wagon so I have experience of both sides.