Canon offers the EF-S 18-55 f/3.5-5.6 IS as the kit lens for Rebels, and the EF-S 18-135mm f/3.5-5.6 IS as the kit lens for the 60D (so I read) and the 7D.
Yet, from the reviews I've read, the 18-55 is the better performer: better IQ, less vignetting, less distortion, etc.
Why is Canon packaging the (supposedly) inferior performer with the higher-end camera? Or, are the reviews wrong?

