I am deeply interested in all things BRLA. 'can't touch this' brings up a very real point about how TMs can create inaccuracies that our systems have no way to measure.
That said, I don't think it is the reason for the majority of errors, at least at my store. I wish I could support that with more than my intuition, but that would be a tall order.
For the most part, I think most of our errors are simply the results of poor training, and extremely inconsistent follow-up and holding to account.
The main issues I see are two-fold.
1) TM's either have trouble counting, or mis-keying qty backstocked, OR mistake two similar items as the same item when backstocking (think shampoo and conditioner).
2) TM's are too quick to say they scanned all items, when they in fact, did not do a sufficient job of looking in the given location.
If you could eliminate these two problems, I think that most stores would see BRLA of 99.5% or higher.
All that said, I have sneaking suspicion that there will be some major changes to backroom accuracy metrics coming in the next year, or sooner. Stay tuned to find out, but, if you're paying attention, notice how much better Backroom Location Audit is compared to a year ago.... That will clue you into some things to come.