Tipping is not just for cows anymore

Every time (and we're talking about once a month, if that) I go through a Starbucks drive-through and see that tip jar, I get SO mad. What exactly are they doing that makes them think they deserve a tip on TOP of the outrageous prices they charge for grinding and whipping up a couple of beans? And why don't I see a tip jar at other drive-throughs? I get so mad that I almost make it past my nervousness that they might spit in my tall Chai before handing it over. But even that doesn't manipulate me into leaving a tip.