It's not about valuing the education on offer, it's about valuing an education.
For example, if a parent thinks that the national curriculum has dumbed down education they can either be a parent who is not invested in their child's education and so does nothing or they can be a parent who values an education and wants their child to do well and so provides additional activities which enhance the education that the child gets.
You can have a child from a family who are in poverty who values an education and seeks to provide educational opportunities even if they don't have much money - they might not be able to travel or go to educational events but they can be encouraged to watch the right programmes on television, to read the right books and so on.
My DS once had a teacher who had the most appalling general knowledge and taught things that were plain wrong, DD used to have a English teacher who admitted to her students that she never read a book and preferred Heat magazine (she's no longer a teacher, she failed her NQT year and left the profession), I knew from what DS had said that her general knowledge was poor, plus I know that the education system in the UK now is so prescriptive that children don't gain much knowledge in schools, they just learn how to do tasks so we worked at home to overcome those shortfalls and my DCs have both done well as a result.