@vonny,
No Vonny, I'm not talking about the tills where you have to scan everything through yourself. Total waste of space those things.
I believe it's called Fast Scan in Sainsburys, and it's where you scan your shop reward card (Nectar in this case) at the entrance and it gives you a scan gun.
Then, as you go round, you scan each item as you put it in your bags which are in the trolley (cart).
When you reach the tills, there are specific fast scan tills allocated, where you hand the gun to the cashier, she blips it on the doo dah and tells you how much you have to pay (you already know this because the running total shows on the gun as you shop - another advantage)
You then hand him or her the coupons which are knocked off the bill, you pay and then go.
No emptying the trooley onto the checkout belt. No repacking back into bags, just in, pay and out.
Usually, from point of arriving at the checkout with a big shop, to leaving the checkout is usually about a minute or two per fast scan customer.
As far as shoplifting is concerned - the system builds in a random check every now and then called a re-scan, which is an inconvenience, but they usually chuck a member of staff your way to unpack and re-pack for you.
I would never go back to the handling three times shopping system again.
Fast Scan is much faster.