Agreed A and C.
The reason for the difficult exam (the knowledge) London black cab drivers have to pass is they play by a clearly defined set of rules.
On the other side of the fence are the minicabs and Ubers who are the Arthur Daleys of the taxi world.
Few checks or regulation means you get what you pay for but these people sadly undermine the legal operators business model.
If I was running an AOC operation I would be extremely angry to see cowboy pilots flying N reg aircraft on illegal charters that cannot be stopped by the CAA?