I am a cashier and it is not my job to know what I am scanning through my register. It is my job to scan the items as quickly as possible. We are timed and we have to scan a minimum number of items per minute or we can get written up. If we took the time to look over every item that every person purchased it would add minutes on to each transaction. I am sure that the customers would not appreciate having to wait in line longer while we examine their groceries.
The computer sometimes will not allow a coupon to go through, it is the cashier's responsibility to make sure the item was actually purchased. If the coupon is expired or the item was not purchased we do not receive the money from the manufacturer. When I ask to see an item that the customer purchased it is not because I am trying to make things difficult, I am just trying to do my job. As a previuos poster mentioned, the descriptions we see on our screen do not provide many details, it is sometimes hard to tell based on that description if the correct item was purchased.
At our store most, if not all of the cashiers handle the coupons in a polite way and do not try to make the customer feel guilty for using them. Cashiers are just like people in general, some are good, some are bad.
I have had my share of "extreme couponers" and some of them are a huge pain to deal with. They get to the check out and are not at all prepared. They start to sort through their coupons and their groceries and it can take a long time to get each separate order ready. We have a weekly double coupon day when we will double 5 coupons on a $25 purchase. Yesterday I had a lady that did 7 separate transactions, each time she had to dig through her cart and then sort her coupons to find the ones that she wanted to use. Then she wrote a check for each separate transaction and she was not in any hurry. I had other customers leave my line because it was taking so long. She tried to use a number of coupons for items that she did not purchase. I just bit my tongue and tried to smile through the whole thing. She ended up buying 10 boxes of Alka Seltzer Plus, seems like a bit much to me. It is people like that her that make it hard for others who are just trying to save a little money.