Teacher’s unions wouldn’t have anything to do with it. /s
They don't. This is mostly on parents and students. Parents sue because their child didn't get the grade they desired. Parents sue because the homework load is too high. Parents sue because their low-achieving child doesn't get to sit in class with the accelerated kids. Parents sue because there IS an accelerated class. Parents sue because math is too hard. Parents sue when their child insists their wrong answer on a test was actually correct. Parents sue if their child is prohibited from texting in class. On and on.
About 60% of high school seniors cannot work the algebra to solve ohm's law problems. (Three terms with two operators: E = I X R) Those students simply don't care.
Video gaming and cellular phones are creating zombie generations; and, parents approve.