If they're not ready for high standard secondary education at 10, there's no disgrace in that, but don't for a moment think they'd be able to cope with s high standard comp either.
But if problems can be identified beforehand and nothing is then done to help them prepare for secondary school, that's a shame, but the responsibility for that , in my view, lies with the parents. They don't normally have 30 or so kids to look after.
If the child doesn't get in to a grammar despite extra help, then that should lead to sighs of relief all round because they'll then be a big fish in a small pool which might well suit them better.
Honestly, what's the real problem here? If you are annoyed by grammar schools you must be just as annoyed by people who, when they are forced to move for work or any other reason,aim for the best school catchment they can afford, rather than live where they'd prefer - as we did. Mea culpa! (As they allegedly say in Latin).
And just so you know, I left school at 15, no grammar school for me. DH got into a Kent grammar but his dad died when he was 14 and he left at 16 for an enginerting apprenticeship, but has studied and worked hard all his life and is now successful in a completely different field.