tomw, 
You know how people do something slightly embarrassing in the coffee shop (or wherever) and then they say "now I can never go back there"?
I have worked in plenty of customer service jobs and let me reassure you that I never remembered anyone for any reason.
"My usual"? I have no idea who you are, sorry.
"I was just here an hour ago"? Nice for you, I did not retain that information.
"I've been waiting for my food for ages"? Hmm, it is possible that I was bad at this.