I know Im late to this thread, but heres my .02 cents anyway.
Because the consequences of giving someone the wrong blood type are pretty severe, when we'd transfuse a patient with a unit from the bank, we'd have TWO people check the unit label against the docs orders & patient's 'chart'. At the bedside, it's TWO RNs checking the wrist band against the label & order.
That's three people independently checking.
You would think something similar would be in place for a snatch & grab.