When I was 11, I had a teacher lean over during class and tell me how much she didn't like me, that I was the laziest student she had ever had, and that she couldn't wait until the end of the year because she wouldn't have to see me any more. To be fair: I wasn't a horrible student, was usually quiet without many friends, and just wasn't at the point to handle 2-3 hours of homework, probably due to undiagnosed issues.

I learned that teachers don't always have your best interests at heart, and I couldn't trust any of them much. I couldn't imagine the stress of trying to impress teachers to the point of getting recommendations, and I can't imagine she'd have given me one and I probably would have been scared to ask the others after that. On the other hand, it also became quite clear that you could game the system a little if you got the teachers to like you.

Just because they don't have to say good things about every kid doesn't mean that all of them will say things that give a fair assessment, though a lot would try a little more than this woman did.