This week marks a year since the launch of an apprenticeship levy on large employers – a good plan to urge them to claim the money back for training. But the sorry result so far has been a catastrophic drop in apprentice numbers in England, with 59% fewer starting in the quarter to November. The Open University found that businesses paid £1.39bn into the levy but drew down just £108m for training, because they wrote off the levy as just another tax.

Some employers reject the new higher standards for apprenticeships that were introduced with the levy. They have been unwilling to create quality apprenticeships that must last at least a year, with a day a week for training courses. What companies had previously badged “apprenticeships” were often low-quality internal training of older staff. Research by the Resolution Foundation found that fewer than half of the trainees even knew they were apprentices.

The shortage of construction skills is the worst ever recorded, with the Construction Industry Training Board reporting a 31,600 shortfall of new skilled workers a year. Without them, there is no hope of building the government’s target of 300,000 new homes. Plenty want to learn those skills, which would lead to well-paid jobs. Yet a rising number of young people – more than 203,400 last year – are taking useless, “dead end” construction courses that leave them with no NVQ and no job. Only 10% are real apprenticeships attached to work: the rest are classroom-only courses offering no recognised qualification, with no employer willing to take them on.

If this cheating of young trainees happened to university students, imagine the political outrage. Look at the scandal involving Learndirect, which is at risk of closure when its contracts with the Department for Education end in July, having been terminated last August after the publication of a damning Ofsted report that rated it “inadequate”. More than half of its apprentice trainees due to finish their course last year failed to achieve their qualification. Yet this former state-run service, privatised by the Cameron government, had £631m state funding since 2011. Gordon Marsden, Labour’s long-serving shadow skills minister, points to other private training companies that have gone bust, leaving trainees with student loan company debts and nothing else – John Frank Training, Focus Training and Edudo among them.

A world of difference divides young people on the university route from all the rest. No one put it more pithily than Paul Johnson, director of the Institute for Fiscal Studies, describing how even he had struggled in his search for apprenticeship choices for his non-academic son. “It is staggeringly hard even to find the right opportunities,” he said, referring to the ease of Ucas compared with the impenetrable thickets of training options.

Everyone salutes gold-standard apprenticeships: more apply for each place at Rolls-Royce, Siemens or British Aerospace than for those at Oxbridge. Higher apprenticeships that offer degrees and earning while you learn, without building up astronomic debt, look a prime option, but they are vanishingly rare. And skills minister Anne Milton told the Commons education committee there is now “middle-class capture” of the few top schemes.

The government has set a target of 3 million apprenticeships by 2020. Even Milton can’t say where this magical number was plucked from, but in order to reach it, any old course, however useless – such as the three-month, low-quality retail courses that don’t lead to jobs – will be rebadged as an apprenticeship. At least now the minimum standard has been raised. Theresa May has announced a review of post-school education but the fear is that it springs less from vocational concern than a search for eye-catching alternatives to Jeremy Corbyn’s free tuition fees that stole her majority. She can’t outbid him, but lower interest rates or lower fees for cheaper university courses is where votes will be won, even though top-quality training is the real economic imperative. As Johnson says: “It is our failure to get enough young people into high-quality, job-based training at 18 that creates our skills shortages, low wages and productivity problems.”

Brexit turbo-charges the need for German-style technical education when the door slams shut on importing the skills we lack. If Brexiteers’ anti-migrant rhetoric had any useful purpose, it should have created a sense of national emergency towards skills training for school-leavers. And if you are looking for multiple causes of the upsurge in knife crime, start with the abysmal flatlining numbers of 16- to 24-year-olds not in education, employment or training; there are still 600,000 of them.

You have to doubt the good faith of a government that has made further education bear the brunt of cuts and cut adult education, including courses teaching English as a second language, which is vital for getting migrants into jobs, especially women, by 60%. No government that causes a 10% drop in trainee nurses by abolishing bursaries can be serious about skill shortages. Policy is made by graduates at Westminster and Whitehall who know nothing but the A-level and degree route they and their children took.

Given her back story, Angela Rayner might radically change priorities if she took over at education: there were strong rumours that this FE–educated politician opposed Labour committing £11bn for free tuition fees for middle-class students. But in all parties, the political demands of the university classes win out. For decades, all governments have claimed good intentions, but they have only reorganised vocational acronyms and myriad confusing qualifications, without resources or genuine political effort. New T-levels for technical courses are supposed to start next year with the high ambition of “parity of esteem” with A-levels, but again they are underprepared and underfunded.

Everyone knows it, everyone admits it, snobbery is endemic. May herself identified social class as the problem: this is about “other people’s children”, she said last month, promising to make Britain a “great meritocracy”. But since her first prime ministerial speech, she has been as good at naming “burning injustices” as she has been bad at solving them. It needs a revolution in political attitudes to focus the next decade on the other half of school-leavers.

• Polly Toynbee is a Guardian columnist

• This article was amended on 12 April 2018 to clarify two points. An earlier version said Learndirect “is about to shut down”, where “is at risk of closure” was meant, and said that “nearly half its trainees fail to get a single qualification”, where “more than half of its apprentice trainees due to finish their course last year failed to achieve their qualification” was meant.