I would encourage customers to recognize that this may be a reason some retail employees respond differently than you might expect. As the parent of a child with autism, I'm around lots of kids whose social skills can be less than ideal. What's hard for casual observers to understand is that these kids are trying - it's just that they "see" the world differently. They also often have to deal with much anxiety and stress at being in work situations that require lots of interaction. They are uncomfortable with eye contact, don't easily make small talk, and may be trying to hide small tics or repetitive motions that help them calm themselves.
Was that the situation with the employee the OP encountered? Of course, I don't know, but just want to remind people that many people in the work force deal with "invisible" disabilities that make their lives challenging.
We have a friend whose son with Aspergers works the check out lane at a major grocery store. While he is able to do the required "greetings," he otherwise focuses only on scanning the items, taking payment, etc., There's no additional eye contact or conversation, and he has some funny motions he makes. I'm sure others in line think he's unfriendly, but he's just doing the job to the best of his ability. His managers really like him, because he's extremely reliable, accurate, and willing to come in to work whenever they need him. He tells his parents he likes the job because he only has to deal with one person at a time!
While these employees can seem less than ideal to the casual shopper, it's actually to all our benefit to have kids like him in the workplace. Rather than becoming a drain on society and having to live off disability, they are supporting themselves - and contributing to social security (for our retirements) rather than having to draw it themselves.
