We currently have a huge number of tiers to our education system.
(1) The highly academically selective privaye schools which are generally accessible only to the wealthy when the child is very bright
(2) The somewhat less academically selective and more nurturing private schools where the children of the wealthy who are somewhat less bright or have additional SEN may go
(3) Highly selective grammar schools "superselectives" that take only the very brightest children from across a wide area
(4) Medium-selective grammar schools with a wider remit taking the above-average-bright children from a smaller area
(5) Faith school comprehensives which don't require money or examination for entrance but do require determination and careful attention and adherence to selection criteria from parents up to 5 years before their child needs a place, thus biasing intake towards the children of the comfortably-off and well-educated who have time and energy to invest over several years
(6) Leafy suburb comprehensives where there is selection by wealth due to house prices in the catchment area being circa £200k more expensive than houses of the same size in areas without an attractive school
(7) A motley selection of other often-unique schools that in some way attract a particular category and often thrive in doing so (e.g. music specialist)
(8) The comprehensives that take all the children who don't qualify for any of the above or whose parents aren't sufficiently engaged with education to care much where they go.
(Obviously also Pupil Referral Units and SEN schools too)
It's obvious that the schools in category 8 are going to end up with a mich higher than average proportion of more challenging pupils and are often a very unpleasant environment.
Labour have already worked out that they can't abolish (1) and (2) - taxing them will make them less accessible and will make the scramble for places at categories (3) to (7) more challenging and cut-throat - this may have a minor knock-on effect of category (8) schools taking a higher number of those who tried and failed to get a place at (3) to (7) type schools which may bounce them a little higher but may not.
All the children in type-(8) comprehensives deserve the education and opportunities that their contemporaries in types (1) to (7) are getting - even the ones who are disengaged with education and are disruptive and chaotic deserve better. It's not like a 13 year old has the maturity to make an informed decision that education isn't worth it for them.
The idea of trying to level the playing field by getting rid of all these different types simply can't work - the legal battles would be ruinous. Getting rid of any one or two categories would not stop there being a multi-tier system so it has to be all-or-nothing. When tony blair got in with "education, education, education" one of the best things they did was to increase category (7) with all sorts of specialist academies with USPs that made them attractive, many of which are thriving and are highly in-demand within their region.
Surely the solution is to do even more of this - gradually managing the unattractive undersubscribed schools to close from lack of demand while creating a plethora of inspiring specialist schools that have a lot of different ways for children to discover and grow their potential without having the number of high-grade GCSEs being the only measure of success.
Unfortunately this will require a lot of money and with 14 years of the wealthy and powerful creaming off everything they can to line their own pockets and make it easier for the rich to get richer while cutting and cutting education (along with all other public services) it will be a long time before any such initiatives can be launched. I think it's more likely that at first it will be as much as labour can be expected to do just to slow down the desperate spiral of decline in the sector