Why, just because you need it to survive? You need food to survive, too. Does that make food a basic human right? I'm sorry, but just because I'm running a restaurant or grocery doesn't make me morally obligated to feed every starving moneyless waif who comes along. I guess that makes me heartless.
errr, bad analogy...
It would be expected from the government, through some charities or similar channels, to provide free food (and shelter?) to those who cannot afford it.
This actually happens nowadays by means of food programs for kids from low income families (usually through schools) and other means of charity.
No one is expecting private doctors to provide free health care nor private restaurants to provide free food.
Your are certainly not obligated but if, however, you feel like giving then why not?