Your coins are senseless (c'mon, that's a good pun).
A dime is smaller than a nickel, but worth twice as much, and also smaller than a penny, which actually costs taxpayers money to produce. They also have nicknames like nickels and dimes that don't tell you anything about their denominations.
Speaking of denomination, nowhere on a quarter does it say 25 cents.
Tipping has no set guidelines.
Even Americans are divided over this issue. There's no set amount or percentage. You're either Mr. Moneybags or a cheapskate, depending on who you're with.
But really. Why do visitors (or anyone) have to pay the price for cheap employers, or pay people to do their jobs even reasonably well?
Take coffee, for example. You'd probably tip the waiter who brought you the cup, but not the guy who brewed it to your liking. One job's not harder than the other -- actually, the barista's job is surely tougher.