Testing of any sorts should be outsourced by the flight schools to the CAA. The CAA should then appoint a testing officer by systematically working through the list of DE’s. The charges from PPL all the way through to ATPL should be as per a standard charge regulated by the CAA.
By doing this there is no incentive to be a ‘nice’ DE, becoming popular and then making more money. When it’s your turn you test, record the result, then wait for the next call from the CAA.
By having a DE testing the students you would also move away from pressure being applied on low time GRII instructs to pass incompetent students.
Monitoring of the flight schools would then become a lot easy for the CAA. Any trend that starts to develop like regular failings from students at a particular school by the now independent DE’s can be investigated.
What you would have is every test by the DE being an assessment of the school standards by a CAA representative.
If a system like this were in place many accidents in the future such as the arrow case above will be avoided.
Well that’s my 2c worth.