&gt;&quot;The very slowest people&quot; are actually the majority: the elderly, the very young, the temporarily or permanently disabled<p>That is quite simply not true. <a href="http:&#x2F;&#x2F;www.censusscope.org&#x2F;us&#x2F;chart_age.html" rel="nofollow">http:&#x2F;&#x2F;www.censusscope.org&#x2F;us&#x2F;chart_age.html</a> As you can clearly see, most of the population falls in the age range that has no trouble walking at a reasonable speed. I don&#x27;t have exact figures on how much of the population is disabled or seriously injured at any given time, but experience says it&#x27;s not enough to make up for the fact that the very young and the very old are very very far from constituting a majority.