So a JW who really wants can accept blood without DAing themselves.
Not true. A great many believing JW's would feel so guilt-stricken from receiving a transfusion accidentally (AKA "not filling out their DPA due to laziness") that they would go to the elders to purge themselves of their guilt. They are then at the mercy of the elders, who decide whether this person should be considered DA'ed or not. And those who did willingly accept a transfusion would more than likely be found out...through hospital liason committee, through other JW's visiting and overhearing, etc. Nothing is truly private when you are a JW. And you can be sure that once the elders find out, you're f**ked.
Interesting you mention that people know full well the policy on blood, DAing and DFing... These are not policies they want the general public to know. They are not revealed until a "bible study" (I use that term loosely) has been well-established. What do I mean? The blood issue isn't raised until chapter 13 of the Bible Teach book. And disfellowshipping?? Not mentioned in the Bible Teach book at all. Oh, no... it's not even mentioned in the follow-up book Worship the Only True God... the "student" must wait until chapter 3 of the God's Love book to be introduced to disfellowshipping (which is a pretty damn cruel irony). Now, how is that disclosure? The "student" is already exhibiting signs of complete thought reform, Watchtower mind control, etc. and may have already gotten baptized by this point (I know quite a few who did as soon as they finished the Bible Teach and Worship God books). So now this is sprung on them, complete with a section in the appendix of exactly how disfellowshipped persons are to be viewed and treated. Now that's some friggin' fine print for ya!! Not all converts know about the DFing policy. And it's not something the WTBTS wants the public to know about. That's why there is no mention of it in the Awake or the public edition of the Watchtower. That's why when I was chatting with a JW online, she was baffled at how a "worldly person" knew so much about DFing. She was shocked. "How do YOU know about disfellowshipping??" It's a dirty little Watchtower secret...one most people don't know about...not even a lot of those who are on the verge of baptism.