I disagree, if I'm driving on the road and I see I can buy some fresh mango juice just by stopping the car and spending a few rupees to get it there and then, it is good for my general wellbeing :) But if I see a stand with old samosas full of flies on them, well even if I'm really hungry I will not buy them. This can happen in your own kitchen as well if you don't cover the samosas after frying them in oil, so the roadside is not to be blamed. Roadside selling is a sustainable way for local people to earn some extra money without spending much resources in transport. It is healthy as long as people are sensible :)