Feeling Tipsy??

Can someone please explain tipping to me?? I mean I guess I understand tipping a waitress or waiter...perhaps even my stylist or the lady who does my nails; I believe those people make little to nothing so they rely on tips...which is fine because it makes them do their job well, or not get a tip, but where does it end??
I had my couches cleaned a few weeks ago and was getting a check ready to leave with my husband so he can pay them. I then said, "crap, I don't have enough cash to tip them" and in turn he looked at me and asked why in the heck we had to tip them. Good point. Why do I have to tip them?? Don't they get paid to do that?
Why do certain professions expect a tip and others don't??
How about we start tipping our teachers? If you educate my son/daughter and get him enthused with learning...here's a tip.
Or our doctors?? Hey you found that weird looking mole before I did...here's a tip.

Why do places like Starbucks (sorry Rachel) have little jars on the counter looking for tips?? Don't you get paid to make my Cafe Mocha (no whipped cream please). And if the pay sucks, isn't that suppose to motivate you to educate yourself and get a job where you aren't making mochachocafrappmachiato's??
I saw a tip jar at Subway!! What??? I came in there to buy a sandwich (actually I hate Subway, I was just buying a gift card for someone...but anywho) and now I have to give you more money to say, gee, thanks for making me a sandwich??
I was helping a friend move and we were following the moving truck to her new home, she said that she needed to stop by the bank to get cash so she can tip the movers. Why I asked? She responded with a "To thank them for doing a good job and not damaging anything"...WHAT?? but isn't that what they are suppose to do?????? Are they "don't always get the job done movers" or "will do a great job as long as we get a tip movers"???
How come I don't get a tip??? I am helping you with your health...and if I make you feel better, shouldn't I get an little somethin-somethin?? I mean I know you already paid me for the treatment, but really that was clearly just a "base-pay", now I need more.

Here's a tip....don't 'tip!