I don't know
why people do it, but I'm not particularly surprised that it happens. My father-in-law wanted a GPS, and I suggested that he buy the same model that I had, since I knew it would do exactly what he wanted and was within his budget.
He bought a second hand, older model by the same manufacturer from e-bay for the same price that mine cost. In use, it's identical to mine, but doesn't have an SD card slot, has a monochrome screen and less accurate sensor. I don't know why he did it, but can only think that he assumed it was a bargain because it was on e-bay.
