I think the issue is largely cultural and financial. There aren't the resources- and by this I mean human resources and physical resources- that there needs to be. There is a one-size-fits-all culture, with teachers being expected to be identikit drones who all teach in the same way, no longer allowed to act as professionals. Standards of behaviour have fallen, and so have the standards expected of children. Children are no longer accountable for bad behaviour and have far too much power/knowledge of their "rights" and are demanding of "respect" (that they have not earned and that they do not give to anyone else), whilst at the same time shrugging off all suggestions of responsibility and accountability for the actions, nor for their educational achievements.
I feel teachers are often containing a class, rather than able to manage any meaningful teaching. I think this is sometimes as they aren't good teachers but I suspect mostly it is to do with class size, the behaviour of the children, the constantly changing educational system and a 100 other factors. I also feel the ideological pushing of SEN children into mainstream school without putting in the resources they need to thrive is a travesty. Teaching is a thankless task and I wouldn't do it "for all the tea in china", as my grandmother used to say.
For this reason, I chose to send my DC to private prep. It is like night and day when compared to the local schools we saw and what I hear about my nephew's school. It has a calm atmosphere, small classes (10-12) with multiple groups within a form to allow this, and wonderful teachers who have time to do their jobs (or so it seems). There is an expectation of good behaviour and manners, rules are clear and strictly adhered to with the disciplinary system very clear. I'm not saying the children ar never badly behaved- I'm sure they are- but low level disruption is uncommon and any episodes of significant bad behaviour seems to be a "scandal" that all the children know about and a rare event. For instance, being sent to see the headmaster is something of a significant event (and something that you REALLY don't want). Headmaster is liked and respected, but a little bit feared by the children. They also seem to genuinely want to please him and make him proud of them.
They have longer days (8-4) but do at least an hour of games per day, and spend a lot of time doing interesting activities. There are specialist teachers for music/IT/PE/languages/science from year 2. From year 3 maths/english/languages and science are "streamed" by ability and extra support for those struggling a bit and those who are academic are stretched at a faster pace. By year 5 they have a form class for some subjects- e.g. PHSE/RE but have specialists for maths/english/foreign languages/latin and classical studies/science/IT/Geography/History and of course music and PE. They continue to be streamed.
When comparing the education my DC receive to that of my DN, I would say they are like night and day. I would say whilst my eldest is only 1.5 years older than my eldest DN, educationally I think DC is at least double that, probably more. I think a some of that is due to financial resources of the school (smaller class sizes and higher pupil:teacher/TA/support staff ration more generally) but I think a lot is due to the fact teachers are respected to teach without being told exactly what they must do and say; and also that behavioural expectations are high and the discipline is there.