Actually, with todays digital technology, the barriers to entry for counterfeiting have been lowered considerably. High resolution scanners and color printers, image editing software... Consider this time of year with shopping madness you don't necessarily have to be an idiot to get burned. It's unrealistic to expect that people are going to have the degree of vigilance necessary to catch every phony bill, especially if it's smaller denominations like 5s and 10's. One law for all can be a hassle at times I suppose but it beats the alternative.

"Democracy is a pathetic belief in the collective wisdom of individual ignorance." - H. L. Mencken