Even that harried, over-worked cashier at the grocery store appreciates being treated like a human. I can't tell you how many times I've been just normally nice, and had someone in that position look at me with honest thanks in their eyes. I've been in that position, and I will never forget it. I've had those blisteringly shitty days and gotten picked up because one customer was friendly, polite, and made me smile.
I want to be that customer.
And the politeness does end up working for you. Simply by being pleasant (and more so than most of the other customers, who seem to be terse for the sake of it) the people at the cafe where I get my breakfast some mornings don't even bother asking me what I want because they already know. One excellent day while I was taking a call, the whole thing was done without a word, and that got me through the awful workday that ensued.
