One of the biggest problems, IMHO, is the classic conflict of interest the various CAA's have. Not only they obliged to police the rules they make, they also decide upon the commercial viability of the very companies who pay their income. Stick rigidly to the rules and a company may not survive in harsh times. (I've flown with various companies who asked for dispensations to limits to overcome difficulties of their own making.) That strands huge numbers of pax, dumps loads of people onto the job market, reduces the income of the 'AA' and generally inconveniences huge numbers of people.
A blind eye for a short period might avert the commercial fallout. Once that is done the relaxation of the rules becomes the norm for that company. Rules are bent everyday, constantly. In general the 'AA's monitor paperwork. In every airline I've worked for the annual audit has only flushed out record keeping and other paperwork errors. Working conditions being outside the guidelines not even noticed or reviewed. In other words, a joke. The "AA's put far too much self regulation on the airlines. An airline applies for an AOC under a raft of proposals. The spectrum is massive. As long as they appear to follow the general guidelines it is approved. Often the terminology is so vague it can be interpreted different ways on different days. Flexibility? Yes. Abuse? Also.
Remember Valujet. The NTSB ridiculed the FAA for having excatly this same conflict of interest in its oversight. It procalimed that the 2 issues, commercialism and operational standards MUST BE DIVIDED. I'm not sure if it ever happened, but it sure as hell ain't been approached in EU. It's about time!!