Because see, green has this other definition, that's much MUCH older, of being a colour, and I keep stumbling into conversations where someone talks about something being green, and it takes me awhile before it clicks that they're not talking about what the word has meant for all of our lives, and then some.
An example was my mother just asking "What's the big deal about a green roof?"
And I'm listening to a discussion about the laser printer health hazards that came to light recently, and someone mentions that they're switching to green toner, and I at first wondered who would want everything they print coming out green instead of black.
There simply has to be a better word we could use. Sure, green works from the marketing guys who want you to think of pretty leaves and saving the Earth, but grah. That second or two where I'm wondering what the hell they're on about drives me buggy.
Someone's gonna tell me their car is green at some point, and I'm going to look at it and go, "Uh, no, it's white..."
Actually, that HAS happened, with my parents' new car, but for different reasons. The paperwork says the colour IS green, but it actually isn't.