It's a bit complicated as there are things that are mandatory according to some agencies and some that are only recommended but not required. You would be surp

It's a bit complicated as there are things that are mandatory according to some agencies and some that are only recommended but not required. You would be surprised but the overwhelming majority of maintenance procedures and their bureaucracy is decided by airplane makers and airlines exactly because local authorities have different or no rules at all. Besides who can know better than Boeing how to maintain a Boeing airplane? Same for other companies. The issues arise when companies know that some procedure is required to be done and logged but shrug it off for whatever reason. Remains to be seen why.