Hi BOAC
I am now reeling in a state of shock to find that there are not just 2 'Alternate Law' programmes but at least 5 (Post #1311) and I am wondering how on earth a human is supposed to work out wtf is going on - or perhaps he/she isn't?
Your latter point is correct to me... they "aren't" (or rather, don't need to).
You do not fundamentally fly the aircraft "differently" in each of the laws. Pull stick back, cows get smaller etc. Yes - Direct Law is a little more "twitchy", but nothing dramatic. Yes - Direct Law needs manual trim, but it tells you that on the AH in Red.
There are "various" flavours of Alternate Law, depending on "how" it got into Altn (or rather, what failed). And they are not fully described in the manuals (nor IMHO do they need to be). If this unique to Airbus? No - I tried reading up the 767 split Control Column / elevator system post the Egyptair accident, and the manuals were again vague - sufficient I would say to fly it, not sufficient to build/mend it, or investigate an accident related to it.
The main difference between the laws is what "protection(s)" are available. In that you never routinely fly to / use those protections, then life goes on as before.
Before over-analysing this accident, we ought to let the BEA analyse it, and see if the stall warnings could have been more helpful. It seems they may have been suppressed at <60K (?) which is pretty much beyond where we expect people to be relying on them, and potentially well beyond certification requirements and controllability?