Thanks for posting that link.
Having read it, it sounds quite believable. The majority of my classes are not as bad as that, but some are very similar. I have had a child walk into a class and grab the legs of another student and try to throw her over a table. She was very surprised that I objected to her behaviour and didn't think that she had done anything wrong as the girl was a friend.
It is not uncommon for children to do no work in lessons unless they are chivied constantly. You often get a mouth full of abuse while you encourage them to work. I once moved a girl who was not working (had given her 3 warnings) and she called me a bitch.
Children coming to class without pens, pencils etc is very common. In lower sets it is not unusual to have a quarter of children forgetting their books in any one lesson.
Large numbers of children will talk, constantly, even when a teacher is giving instructions for activities (which are often interesting), you then spend another 10 minutes telling the kids what they have to do, as they ignored you the first 3 times.
I think that the standards of behaviour in class would be a nasty shock to most parents. I know that it came as a shock to me when I first went into a classroom 3 years ago. It is very different to when I was in school in the 60s and 70s. Some changes have been for the better. But the behaviour in class is much worse, and this is to the detriment of the pupil's learning.