I Have to Tip for What???

I realize I've said this before, but I think this tipping thing is getting out of control. Everywhere I go lately it seems they're asking for tips. Even the donut shop has a tip line on the receipt - the donut shop! How about this: I ask for a donut, you hand me one, I pay, end of transaction. Does there really need to be a tip involved??? I don't get it. Now remember, I made my living on tips for a long, long time, so please don't think I'm anti-tip. When you're being served in a sit-down restaurant, obviously you tip. If you're at a counter and someone does something above and beyond, you may certainly tip. But why must I tip to pick up a to-go order? Where's the logic in that? Why does every place ask for a tip these days? What am I tipping for?