Knowing the ABCDs
Unfortunately the whole world is going down the route of knowing the Question Bank. And, yes, open questions do test someones knowledge but does take hours to mark. I know, I set open question home work (open book obviously) only 10 students but nearly 15 hours of good marking. (If you don't want to explain everything in class afterwards). If you have hours to use in class then just looking through the papers to find all the weak points still takes a couple of hours.
As to the point of Pilot16, how much are you willing to pay for exams, it will need to be a lot more than 60 pounds. I think that people are asked to pay enough without adding thousands more.
The only hope is that Airlines do a good job of sifting out the ABCDers and the people who really know their stuff.