Why do people do that

I cannot fathom for the love of god how can people walk and read ! I know some people are very adept at multi tasking (though there is credible proof to the fact that human beings actually 'cannot ' multi task. We can only move from one task to another. Some can do it real fast giving the semblance of multi tasking ) 

Walking and reading takes it to a whole new level though. The pair of eyes are supposed to guide one on the road. If they are engrossed in reading - hmm - how do you walk in the right pace ? That's why I have seen such people being a major stumbling block for pedestrian traffic . They amble at their own leisurely pace forcing those behind them to reduce momentum. Or if they walk at a normal rate I cannot imagine how can they savour the delights of the book. Are they not neglecting some brilliant pieces by the author when they are concentrating on manoeuvring the road ? What is the need to read and walk? More importantly is it possible to do them both together ? I cannot even flip through pics of a glamour magazine while walking. People walking  with their e-readers and thick novels completely beats me.