This story from Costa Rica says that the failure rate of a new driving test – a preliminary one, which learners have to pass before they can drive unaided – 
is 65%. It says that causes of failure have shaking hands, knocking over cones, not being able to reverse, and even knocking over the examiner!
Apparently, those who have hit the examiner claim it was just “bad luck”. However, the Costa Rican Times correctly asks if it would still be “bad luck” if they knocked over a child while out on their own. Some individuals have failed 15 times so far.
But it seems that Costa Rica has exactly the same problems that we do, with a surfeit of cynical know-it-alls. It goes on to suggest that since the test costs $10, it is possible that people are failed deliberately in order to increase revenue, and it cites failed candidates claiming that the test and examiners are “too strict”.
People the world over need to get it into their heads that ANY system run by human beings is open to corruption. A small amount cannot be proven, but a large amount can. Trying to talk one up into the other is the favoured approach of the typical looney/conspiracy theorist.