Indeed, I've seldom needed more than GCSE math (level of a 16 year old in the UK) in fact I can think of only a handful of times I've needed A-Level equivalent

Indeed, I've seldom needed more than GCSE math (level of a 16 year old in the UK) in fact I can think of only a handful of times I've needed A-Level equivalent math (on notable occasion was solar insolation calculations). It's just not a big issue in the life of a typical enterprise developer.