MRO maint contracts
Having been involved in a few aircraft sent to MRO organisations and also returning them to service I can say that the work done is ONLY what the WRITTEN CONTRACT between the owner and the MRO states unless a further extension and further work is agreed to. Aircraft are always returned with defects outside the contract agreement still open.
If your aircraft is returned with open defects it is because the owner eg QF, has decided not to have the defects cleared at the MRO. It is not the MRO's fault that it still open it is the customer who decided where, when, and what gets done.
The contracts for C and D checks can and do sometimes run into 100's of pages of legal documents on who is resposible for what. This is all run by the owner i.e. the one that pays the bills in the end.