I'm newly signed up on this forum, but I too drive HGVs, and so this thread kind of leapt off the screen!
I agree with you that, if the mirrors are properly set, then, contrary to popular opinion, lorries have no blind spot
But have you ever tried telling another lorry driver that he has his mirrors set up wrongly? No chance!
If anybody in the cycling fraternity could provide me with the opportunity, I would be able to demonstrate that it is possible for any HGV driver to remain stationary, parallel to the kerb, and follow the progress of a pedestrian or cyclist, from a long way down the street, all the way down the length of the trailer, and underneath the nearside cab window until he or she emerges in front of the HGV and clear of danger. At no time is it unavoidable that the pedestrian or cyclist would disappear from the driver's view
It works in exactly the same way if the vehicle is moving - it's just harder to demonstrate!
Bottom Bracket
Cyclists can filter up the inside or overtake outside or come from any direction and if there were enough mirrors to see them all then the driver would not have enough eyes to look in them all and still watch the road ahead. But there are other accidents that cannot be explained by blind spots. I've been overtaken by cars that then turn left, by vans that then turn left and by lorries that then turn left and the lorries are the biggest danger by far.
On Saturday I went up the Cambridge on the A1M. I'd normally go up on the M11 but it was closed because a lorry had smashed into the back of a coach on the hard shoulder. How did the lorry driver not see a bloody coach on a bloody motorway? The driver was one of the people who died so I guess we'll never know that, but if lorry drivers can't see a coach in front of them how are they ever going to see a bicycle in a town with a street plan that wasn't even designed for motor traffic?
Looking through news reports it seems that lorry/coach collisions on motorways are actually more common than lorry/bike incidents in towns. For some reason it attracts less media attention and there are no initiatives to make motorways safer for coach parties.