I have to say it is not just teenager cashiers who are treated rudely. I was in Orlando one year on vacation and went to a local grocery store for a few items. There was a woman in front of me who had food stamps/WIC. The cashier was an older lady, so it was rich the way she handled the woman. Well, the problem was the lady tried to get brand name canned milk and the register would not ring it up. The lady got hysterical. The cashier told her she could not get that milk. That she had to get the store brand. She went into a rage that her kids would drink no other CANNED milk but that brand. Ok, what kids drink CANNED milk?

Anyway, the manager came over and told the lady she would get store brand or none. So, she took the store brand. As she left, the cashier said "She should be thankful she is getting ANY milk. She is not working and getting this stuff for free and yelling at me...a person who is working for a living to help support her." The bagger snickered and agreed and I just shook my head in agreement.
I have only had 2 complaints with cashiers.......both were younger. One worked at 7-11 and was barely legal enough to sell alcohol. Anyway, I went to the store to buy my hubby a pack of cigarettes. Did not have my ID and he refused to sell them to me. I told him I was old enough and he got an attitude. Told me to get my ID. I said fine, I would be right back with my ID. he said sarcastically "Sure you will

" OK, so I went to the house for ID and purposely went back to Mr. Smarty pants. Showed him my ID and he was embarrassed that I proved him wrong. The other one was at a grocery store. It was our anniversary and we stopped to get some beer and wine. Hubby put the stuff on the conveyor belt and I pulled the money out to pay for it. He said "I need your ID". OH great. It was in the car. I then handed the money to my husband and the guy said "No, he can't pay or it. It's YOUR purchase".

I had to go to my car for the ID. I handed the money to my husband and let him pay for it. I was clearly much much older than the cashier. Even the people in line were appauled.