The problem is, if you nationalised it which board do you nationalise?
there’s three big ones. Suppose you nationalise OCR. Let’s leave aside the difficulties that the people who write the papers for OCR almost certainly write IGCSE and other papers as well and that questions go through the OCR testing process.
edexcel and the others are now banned from competing in the U.K. market.
that’s clearly unfair. The government would essentially have chosen one to nationalise and the others to just stop doing what they are doing.
it would be subject to various legal challenges - restraint of trade etc.
consider if it was car manufacturing. The government nationalises Land Rover - fine. It then bans all other cars from sale in the U.K. so that everyone has to use Land Rover - not fine and breaks any number of laws.
so they could nationalise OCR. But they can’t ban the others from writing and selling their exams.
when Gove introduced the new GCSEs most state schools switched to IGCSE - the old ones that the exam boards were still running and were still
available.
Gove had to say that the IGCSEs didn’t count in the league tables to force state schools to switch, and most private schools still haven’t because the reformed GCSEs aren’t noticeably better and in some ways are worse.
the exam boards make a good living writing and selling qualifications that the U.K. has abandoned - o levels, IGcSEs (old style GCSEs) etc.