Look at it this way.
Teacher XYZ stands in front of her class six hours a day. She teaches ALL children in her class from the same textbook and she uses the same methods.
She takes roll in the morning only to see that 4 of her 27 students aren't there again today.
She knows that Timmy comes from a strong home with parents who help him with homework, get him to bed on time, and support her when Timmy occasionally screws up.
Now Janie is a good girl. Her mom helps her all she can. She works two jobs but she still manages to help Janie and go to as many of her school events as possible. Janie struggles some so her teacher knows she'll have to take time away from successful Timmy to help Janie. No problem though because Timmy still gets lots more help at home.
Now little Heyward on the other hand has real issues. His dad beat his mother up and went to jail. Mom frequents bars, drinks heavily and brings home numerous "uncles". She doesn't like Heyward to get in her way. She doesn't care if he stays out late, gets up on time for school, eats or even attends school. Heyward is pretty much on his own. He tries to go to school but the kids tease him and he skips 2 days a week. When he's there, the teacher takes time away from Timmy and Janie just to help him keep his head above water.
Now it's state testing day. Jimmy is rested. Mom and dad have told him they're proud of him and they know he'll work hard on this test.
Janie's mom has tried to prepare her. She's not really up on new methods though. She gives her encouragement, tells her to be sure to eat the free breakfast at school and wishes her well.
Heyward's mommy isn't aware there's even such a thing as a state test. She could care less how he does on the test because she dropped out and can still afford her bar tab with her government check.
Are you following? This is our local district. This was described to me by a fantastic teacher when she told me of her daily struggles. It breaks her hear that she can't help Heyward as much as she wants to.
So yeah, you pay her salary with your taxes, just like I do. Hell, she pays part of her own salary, probably more of a chunk than you do.