DS1 walked short distances all the time from 10 or 11 months because I couldn't carry him due to my hips (I was pregnant with DS2) and if it was only a short distance I didn't see the point in taking the pram. In shopping centres he was always in the pram or the trolley but only because I couldn't physically run after him if he ran off so it seemed safest. Rule of thumb though, if a stranger deems it important enough to tell you that you are parenting wrong, you can safely assume they were unsure of what they were doing themselves when they parented so are probably not the sort of people you want to take advice from.