The lawyers
I agree with the sentiments expressed re lawyers, one of my engineering friends once said that if you take the EASA requirements and replace the word 'safety' with 'liability' then they actually begin to make sense!!!!
I wish the authority had some faith in the discretion of the people they approved to do maintenance i.e. the licensed engineers, but i suppose this attitude is spoiled by a small number of engineers who are more interested in money than safety (change for liability if you wish, it's the same result!) who then take on work beyond their level of approval and then illegally certify for money.
Of course a number of so called operators also muscle in to threaten engineers jobs if they won't comply!
It is down to human nature and individual conscience to decide ultimately what work on any aircraft will be done, just because an item is certified as being done does not mean it actually has been.
At the end of the day it is down to the manufacturers to mandate what work is required to be done as a minimum to keep their aircraft safe and then down to the responsible authority to ensure that these are carried out fairly and correctly.
I have been in aviation for 30 years and since the start all I have heard is that the bosses of maintenance companies want a level playing field.