iMacs come with ONE button...in fact, I think all of them come with ONE button. Stupid design. Most techs I know agree wholeheartedly.
And there's your problem. Macs are not designed for techs, they are designed for normal people. You and I have no trouble with 5-button mice and scroll wheels, but not everyone is as comfortable with computers. Macs are designed to be completely usable with one button, while taking advantage of extra buttons if available, which seems like a good decision to me. I do agree that the "professional" Mac models (G4 towers) should ship with a multi-button mouse, but it's a minor quibble.
Do any of these "techs" actually know how a Macintosh operates or are they the typical tech that only supports what their $5,000 MSCE course taught them? And what is a tech? Someone that works for me, an Administrator. If you are focused on the number of buttons on your mouse, it sounds like a personal problem. The fewer number input devices required to run a computer is better not more. A computer is supposed to reduce work load not increase confusion.