no one forced them to take that job, if they don't care about it don't take it... "not paying me enough" isn't really a good reason to act like an a$$hole when the job description they agreed to is being followed. If people are asked to do things that aren't in their job description, "not paying me enough" can be a valid excuse... but I'm pretty sure the Fast Food Cashier job description has something to the effect of being polite, friendly, accomodating, and always making the customer feel welcome.
There are some that are just @ssholes all the time and then I would agree. But the crap that some of these employees have to go through, they don't pay you enough to have to put up with what some customers and employees put you through. I worked at a KFC from when i was 15 - 19 as a "cook". At the time I had to pay for gas and insurance on my vehicle, plus anything else I wanted, while in Highschool so I worked 40 hour weeks (or close to 40 hour weeks) along with the other cooks. To get the extra hours though, I needed to learn the front counter and work the register, and you can't imagine what some people put you through up there. I had one customer order 2 of the family meals, customer took them and was fine. He came back 20 minutes later irrate at me for not including paper plates and plastic utensils. He demanded free food and when i said I couldn't do that, but I would be happy to give him plates and forks (something they will give out for free IF YOU ASK) he said that wasn't good enough and he should be compensated for his "troubles" and that I should have known that by ordering all that food, he was having a family get together at a local park, and that the kids were all complaining vcause they were hungry and he couldn't serve them food without plates and forks. I told him only a manager could give him free food, and that the manager was not in and had left for the day. He demanded to speak to someone at that moment so I went to the back and gave him the managers home phone number. He then asked to use our phone to call him and I told him to find the payphone down the street, cause its against store policy to allow a customer in the back. He stormed out and I received a call from the manager saying to give him what he wanted becuase if he complained to head office, thats what they would do, So I packed it up ready to go for when he came in. He demanded that i apologise to him, and I told him I did nothing wrong, he said I did and that obviously the manager agrees because he got what he wanted, and I told him I followed store policy. He told me then he would report me and my attitude to the manager the next day and have me fired. i told him good luck, I look forward to it. I kept my cool and laughed it all off while he was becoming irrate because under $7 an hour is not worth it in my opinion to get worked up about something like that, when most of the other female employees that did that job would have been brought to tears in that situation.
When it came to the minimum wage jobs that I have had, I always did my best and what was asked of me, but I never went over and beyond, and never took things personally or cared much about the job because it was just that, a minimum wage job that was to earn me some extra spending money.