Well, I wouldn't withhold the information!
I would say it makes a huge difference if the student is continuing at that school, ie. there's a sixth form & the child intends to study there.
I teach English in a good/outstanding & heavily oversubscribed 11-16 comp. We (teachers) have a full break down of how students have done on individual questions, & if we're talking re-sit after the November exam, obviously I'd sit down & say 'Right, you did really well on the writing tasks, but what went wrong with the poetry? Either we need to look at your essay writing or your revision wasn't much cop - which do you think?' or whatever.
But for the June exams, they're off to college (or not, if they've not got the grades...).
School does not, to be blunt, give a chuff about them at this stage unless they're a 'near miss' who might benefit from a re-mark.
It may be different where there are internal sixth forms & possible year 12 re-sits are still the school's responsibility, but for us, a student who'd had a disappointing result & wanted detailed feedback would have to actively chase up the teacher/HOD concerned. Otherwise, we're focusing on September's classes at this stage, tbh.