And I think the nature of the maths taught is important. For some students pure maths is appropriate, but for the vast majority there needs to be practical arithmetic that will prove useful in their future lives.
One of my DDs simply could not do maths as dictated by the curriculum. She failed to pass GCSE 3 times - she got a D each time, so this meant that she was not wholly ignorant on the subject, but failed to achieve the desired C. When she was at 6th form, she was forced to continue to try and achieve this, and it was the bane of her life. In the end I spoke to the teacher and said: "Look, she is a D as far as maths is concerned. We have 3 results as evidence of this. She accepts that this is her level. What are we trying to achieve here?" She was allowed to drop maths.
She was offered an unconditional place at a Russell Group university and achieved an MA. She now runs a highly successful business with her OH.