I am not a teacher but I do have a son-in-law who is a math teacher at a middle school. He is so good that parents sought to put their kids in his class. He has been telling me that many of the kids are not doing their homework and he has been getting complaints from the parents when he gave their kids poor grades. So blaming the teachers is a cop-out for poor parenting. 

However, I do blame the administrators and school boards for undercutting the teachers instead of helping them and getting tough with the parents. Besides being at the mercy of the government and the taxpayers for their job and pay, they are also forced to teach to the test and to stick to approved cirrulums only.