I am sure that highly fit 20-30 year olds who train for marathons can manage.

I am not sure how that translates to everyday commute for tens of millions of people of all fitness levels and ages.

This 'if I can do it then surely everyone can do it' attitude is incredibly myopic given the scale of the issue. You represent less than 1% of the population (A total of 1% of Aussies report cycling to work once a month or more). Your views don't matter or don't apply for the other 99%.