Please explain exam boards to me: why so many? Why doesn't the DofE do it?

I think OP might be suggesting "it's not fair".

Don't forget though OP, if exams in any year are apparently "easier" the exam boards set boundaries to reflect this, so that comparable results are available across all years and all boards.

private exam boards were thought to introduce healthy competition to the sector- but they have played a part in the very confusing and complex qualification structures in the uk. European countries, for example, will have one, state approved, way of qualifying a plumber. The uk have a plethora of different awarding bodies competing to offer plumbing qualifications. It’s mad if you ask me, it’s also hugely expensive for schools and colleges who work with up to 50 different awarding bodies with different fees, software platforms etc. hugely costly to the taxpayer.

It isn’t done by the department of education because these exams and these exam boards have been in existence much longer than the department of education has.

the department of education as a central government thing only really started in Victorian times. The exam boards already existed.

why nationalise something that already existed and was working fine?

"Are you implying that the content and difficulty are comparable, so it is not easier to get high grades with one board than with another", I'm not implying it, I'm directly saying it.
Each AO interprets criteria in slightly different way but they have to have parity with all other AOs.

DfE remit isn't to create and administer exams, it's remit is policy + funding etc. They don't "outsource" because it isn't something they are involved in.

It is a highly regulated sector.

So in the U.K. there are multiple exam boards.

OCR came out of Oxford and Cambridge exam board and I think is owned by the university of Cambridge

Edexcel is owned by Pearson and conglomerate.

there’ also AQA, WJEC (Welsh exam board) and a few others.

yep privately owned.

schools pay exam entry fees for each student to enter GCSEs or a levels or BTECs and that’s where their income comes from.

lots also do international qualifications - so IGCSE which many schools abroad enter students for, also international a levels.

in some subjects there are a lot of differences between exam boards. In others not so much. Maths gcse for example is quite similar. Maths a level the same.

yes each school is free to choose which exam board to use although Gove stopped U.K. state schools entering students for international GCSEs.

we have multiple exam boards because they have always been there.

the university of Cambridge has been setting exams since about the twelfth century. In this country education and qualifications have been around a lot lot longer than state education (1870 compulsory state education) or a national curriculum (1988).

one exam board, city and guilds who offer vocational qualifications came out of the medieval guild system of craftsmen and craft qualifications.

I think in the past different universities produced different exams. My O levels and A levels were university of London and generally considered more rigorous than some - grammar school. Strangely I seem to remember Cambridge being considered an 'easier' option. This was 40+ years ago though.

I've nothing meaningful to add, but did spend a couple of minutes scratching my head, wondering what the Duke of Edinburgh had to do with exams!

I work for an exam board.

They are all private businesses
Schools can choose which ones they use
They all have to follow the qualification specs laid down by Ofqual
Ofqual oversee production of every syllabus and exam
Ofqual and JCQ lay down rigorous assurance of exam boards
Schools pay out of their budgets
Education is devolved in Wales, Scotland and Ireland hence need for different exam boards there
We have different exam boards to prevent a monopoly by 1