It Always Happens to Me

Am I the only one who gets a case of 'check out rage" when I go to the grocery store?  Almost 100% of the time, I will be in line and either I'll get behind someone who has 68 coupons or their cash card won't work.  Or they need to 'check a price' on something in the back of the store.
Then another cashier will appear and say, 'can I help someone over here?' and the 2 people BEHIND me will get in that line.  Makes my blood boil....