Forget about tipping in a restaurant, everyone knows to tip there except for really shoddy service, just as they know to tip extra for exceptional service.
If someone (whom I don't know) does something for me that saves me considerable effort from having do it myself, then I consider tipping. If the person that helps me is making grandiose amounts of money doing their job, then I don't consider tipping, but will keep in mind that I'm obligated to them in some fashion.
In most cases, you know if someone is making good money or not. The truck driver bringing your big iron doesn't make fantastic amounts of money doing his job, so you know that if he does something voluntarily that saves you effort, that it's a good idea to show your appreciation. It's all a matter of showing your appreciation and deciding if money is a suitable method for showing that appreciation. If not, then you express appreciation some other way.