Whaaaaaat?
I only work two days a week at a bike shop and I've sold and installed no less than a dozen Speedplay replacement cleats since Christmas. We sell a lot of the covers too... people are always misplacing them/losing one of them.
We carry Look, Shimano, Speedplay and Crank Brothers. Truthfully they're all equally as popular (in terms of units). I've definitely gotten the feedback that Looks are easier to unclip/clip into than Shimanos, but I have zero issues with my Shimano pedals.