"Saffron-colored robes"

Yesterday, I asked what color saffron is (yellow) and why everyone keeps talking about the Burmese monks "in their saffron-colored robes" when, pretty clearly, they don't wear saffron-colored robes.

I got email from a weaver-and-dyer who said "Saffron's dye is a beautiful bright, clear yellow and the monks' robes are dyed with turmeric or some other natural vegetable dye readily available in their countries. ... I have been using saffron as a dye for cotton, silk and wool as part of my research which is why I can definitely tell you the robes are NOT dyed with it."

I also got email from someone who said she thought she remembered monks with yellow robes in pictures of protests in Viet Nam. Now, that rang a bell. A bit of googling and voila - monks in Viet Nam and Cambodia and Thailand in actual "saffron-colored robes".
So, I wonder, is that the source of this notion that all Buddhist monks wear "saffron-colored robes"? The famous monks - the first ones, probably, to really impinge on the American consciousness, immolating themselves in protest on the streets of Viet Nam - actually did wear saffron. Did the phrase take hold, and then our ignorance of other cultures did the rest? Some do, ergo, all do? When I'm describing a Buddhist monk, I reach for the invariable phrase in my best Homeric style? All dawns are rosy-fingered, all seas wine-dark, and all Buddhist monks robed in saffron?

And that makes me wonder something else:

This guy to the left is a monk - a Franciscan. He's wearing brown robes... does that mean we're going to assume that all Christian monks wear brown robes? So that if we saw this other guy, we would describe his "brown robes" - or would we say, "Hey. I know what brown is, and that's not it." ?