Why is it so difficult to get a "7" in the Writing Tasks?

Why is it so hard to get that seven? 

When I first read tonight's essay up in the garage, it seemed to have supported its arguments, it flowed well, had complex sentences, and theren't weren't too many grammar errors at first glance. A Band 7 essay, I thought.
 
Then I took a closer look at it.

 
One of the main problems was one that many people have: he wrote a "generic task two" without regard to the exact type of question that he was answering.  If this had been a "to what extent do you agree or disagree" question, it would have received a higher mark in task response. In Band7, there's the requirement in TR that says "maintains a consistent position throughout", and you need to do that differently in a "give your opinion" essay than you do a agree/diagree or adv/disadvantage essay. 

A little closer attention to some of the most basic rules of grammar, capitalization and punctuation, then the very good complex sentences might have carried it.



So, to answer my own question, it's hard to get a 7 because if you make a big mistake in any ONE of the marking criteria, and get a 6, you'll need an 8 in one of the other three to make up for it.