It’s not about passing! It’s about getting a high enough percentage that you actually get into the school! Let’s say the pass mark is 75% and both your hypothetical children are perfectly capable of achieving that. However, the grammar school is oversubscribed so in reality no-one scoring less than 92% will get in.
That’s why parents pay for tutoring. NOT to push a not very able child over the 75% Pass line, but to increase the percentage they get in the hope they’ll get into the school.
No, it’s not fair but that’s the fault of the previous governments who got rid of so many grammar schools. I paid for tutoring for DC to achieve the absolute very best mark they could because I knew that a Pass (ie 75% or whatever) was o longer enough. They actually got excellent marks in their practice papers but I still paid because I needed to get the very best out of them and for them to not drop a mark. This grammar school is highly competitive - because it’s one of few. I paid for minimum tutoring so the tutor could assess them, pass on any tips, etc, and then I did a lot of the practice myself with DC.
If the 70s government (?) hadn’t destroyed the system, we would still have a grammar school 5 minutes drive away and a simple Pass would have been enough. Now DC travels for an hour morning and evening to get to the grammar in the next county.
Why didn’t I send DC to the local comp? Because they can’t control the poorly behaved children there; what they teach is taught at such a low level; they didn’t have the subjects DC wanted to do - and DC themselves refused to go there because it was so unpleasant.
If I hadn’t had the money for tutoring, I’d have done it myself.