Using a checkout, what is this quaint custom of which you speak?
Carry a beepy wand (I think that's the technical name they use) and avoid staff, price checks, queues (so far) and even wondering how much you have spent.
Also, your shopping is in the bags ready to go, no hefting from trolley to checkout to bag-in-trolley again.
They had them in Waitrose about a million years ago but they stopped using them although I think they may be back now there too.
Perhaps this is the reason for the profit plummet since one of the assistants gossiped that she had checked one trolley and found it to be over £76 pounds short of the true total. "Oh, my little one was doing the scanning! I didn't realise. yeah, I'm sure".
I imagine few people over scan so I wonder of this brilliant system will continue, it does save on checkout staff of course.
Me, I love it, I can even bear to buy only three or four items quickly now.