A nice soft forest floor described in that link is a completely different environment than an urban street/sidewalk. Glass would erode completely differently i

A nice soft forest floor described in that link is a completely different environment than an urban street/sidewalk. Glass would erode completely differently in those environments. Of course even in an urban environment the average piece of glass would still take a long long time to have its sharp edges smoothed. I can't disagree with the idea that walking around barefoot in the city is not the best idea ;P