High Failing rate - how is that possible

It has come to my attention that there may be problems with the Centurion Testing Ground regarding the passing rate on the Learners Licences

Centurion has been the centre with the highest failing rate off all the surroundings centres.

Even the driving schools advice parents NOT to book appointments with Centurion Testing Ground because of the failing rate – they advise the parents to rather book with Midrand or even as far as Watloo and Johannesburg centres but NOT Centurion

I have been a Centurion citizen all my live and now that my son needs to write his Learners License, he will be going to Centurion next week for the 3rd time. All his school friends has written the test also 3 times, then went to Midrand or Watloo and got it the first time

I just like to know how this is possible, even the methods of testing is different between Midrand and Centurion, Midrand still writes the manual test and Centurion EVERYONE fails