Obviously, this would be different in a selective or other high ranking school, but in most high schools, teachers choose to focus on the top end because they can get more out of them.
As a selective student who did quite well in all English subjects I'd have to say with a little reluctance that we did get priority treatment when asking teachers to read over essays or creative writing pieces or for any other help we required. But this was mostly in Year 11 and the start of Year 12. Our English department actually began assisting some, but not all, of the lower performing students because they specifically asked for it. Some students are lazy and did not care about their English marks and this was reflected in their poor ranks and marks and the minimal effort made through out the year. But for those who sought out help, some even approaching the students who were in the top end, their marks did significantly increase. I remember that a few students regularly emailed teachers for help and by the end of the year, they went from averaging 11-12s/20 to averaging 16-17s/20, while the top students weren't really given priority treatment any more. I think the problem with giving the top students priority is that you end up with a cohort that is strong only at the top (at our school it was probably the top 25 students or so that were in sure Band 6 region), while the lower end of the cohort (again the last 25 students out of the 126) performs very weakly and so the spread of marks becomes very large. This might affect moderation negatively (I don't know much about moderation, correct me if I'm wrong) and not benefit the cohort overall as well as it could have if the bottom kids performed better, even if you have some people supposedly 'carrying' the grade. In this manner, the school's reputation/ranking in the state, and teachers too, suffer detriment. There is no point in having a strong head but a weak tail. The stronger kids will benefit if the bottom kids do better, so as a top student, you should be grateful that teachers assist the lower performing children as much as possible. But then of course if they are completely neglecting your existence rather than just not prioritising you that's another story.
I'm not sure if you can call a teacher who is trying to help the poor performing kids a 'bad teacher'. It's obvious that the lower performing kids require more assistance than the higher performing kids so it makes sense for the teacher to apply their attention accordingly. Student motivation is always a problem but a passionate teacher takes it upon themselves to try and help all students achieve and perform which involves solving the motivation problem. They might get tunnel vision and forget about the higher performing students, but realistically speaking, how much more help does a top performing student need from a teacher? If a student is high performing then they have skills and abilities in their subject and that already gives them an advantage, especially in subjects like English. How bad is this 'ignoring' your teacher is doing? If your top is struggling to grasp the concepts of each module then you need to see the teacher personally after class and maybe talk about it. Teachers will want to help those struggling, and as students at the top don't appear to be needing help, the lower performing students rightfully get priority. I think it's selfish to expect that as a top performing student you should be getting equal attention to those who are struggling to perform, but that's just me.