This is an interesting thread.... if we ignore the upset/crossness on it.
One thing that really strikes me is just how many of us remember being really moved by seeing a stranger give some acknowledgement when we've lost someone - I have exactly the same thing - when it was my grandma's funeral a jogger going past touched his (baseball) cap and somehow there was something very consoling in that!
But also, there is lots that I didn't know about customs - I'd never heard of the collar-touching thing, or everyone on the street drawing curtains. I guess it's because deaths happen so rarely (to most of us) that some of these things don't get passed on. When Grandma died my brother and I had a sense that our parents' generation knew exactly how to behave without it ever being talked about.
Maybe we should be actively trying to share some of these customs and bringing them back, because they do seem to help and it would be sad if they all died out.
Incidentally, the area where I agree with MadameZ is that the Telegraph article does seem very outraged about a few particular instances for which there might have been a good reason - I disagree that it is generally ok to cut up a cortege, but if it did happen it might have been for a reason out of the ordinary rather than general impatience.