1. HN discussions themselves. Literally EVERY TIME this comes up, you see a massive back and forth from various crowds of GDPR; some of whom swear that it's perfectly comprehensible even as significant portions of the conversation are interpreting the same points in a variety of ways. (Are IPs PII? What exceptions can be allowed? What falls under "security requirement"? What forms of data are associated PII? What sort of deanonymization is sufficient? IS it sufficient? are some common questions I saw in the past, not even getting into the wonderful world of third party data processors.) This seems like enough pragmatic evidence that a (to give the benefit of the doubt) educated and professional community hasn't reached consensus, so to say there's a variety of interpretation seems very fair.
2. I implemented GDPR for a small corner of a notable BigCo. I do not consider myself an expert, but I certainly got my marching orders from experts, (The legal teams who interpreted the document and evaluated the implementation methods) and the sheer amount of horsepower put behind finding an interpretation we believed and were confident in was staggering. Granted this is something where we _really wanted to get it right_ but if it were really trivial to interpret I question if the process would have been as intensive as it was. (To preempt the inevitable; our (my team's) business model has _literally nothing_ to do with your data, but we had many of the same confusions/questions that I saw from companies who did, so I'd be hesitant to say that the burden isn't somewhat widespread.)