Some of the tests to become a train driver, I believe was peer reviewed by a cauliflower. The peer review world is corrupt. I know, because I worked in advertising, before becoming a research fellow at a Think-Tank. Nothing is what it seems, and there are frauds, and dishonest people everywhere. Businesses today that are zombies, who can barely make their interest payments are valued at over $45 billion, are only going concerns purely because the Central Bank is intravenously feeding them QE, but to the public the narrative is "all is well and good".
I don't trust the OPC, due to its opaqueness. They have a monopoly, and it's in their interest to have a revolving door or clients. The days of taking people, politicians, and companies at face value was over circa 1990. They lie in their own self interest. Don't judge a company by its words, but by its deeds. From my perspective the opaqueness of the OPC's scoring for testing is one of concern. Nobody knows what they officially are, and the OPC never lets on. Why?
If you want to be a member of the SAS special forces, you know from the outset, what fitness level, shooting accuracy, pain threshold etc you need to attain. You want to be a typist, you'll know they want a minimum of 60 words per minute. The same applies in multiple fields. You want to know how many lines to achieve, and incorrect answers to achieve an enhanced Group Bourdon score, and it's shrouded in secrecy greater than the riddle of the Sphinx. You fail a computer test, and their is no feedback, or computer verification what your score was, IE: The attainment score needed was 78/100, and you scored 76, followed by a print-out of the questions you got right, and the ones you got wrong.
This gives the OPC enormous power, with zero oversight. They could be running a rigged ship, and nobody would know. Then we come back to that magic word, TRUST! There's an old saying, Trust, but verify. With the OPC, no verification can be done. You simply have to take their word for it. Any testing procedure where negligible, to zero feedback is given, where it's either a pass or fail, and you are not even told where you failed is not a good system.