Why are you railing on this walking in the heat bit so hard? It's your second post mentioning it and I never said anything like that in the first place.
At 18 you should be able to pay for yourself. Stop mooching off your parents.
You're implying that he should go by himself and get food, he could do that, but he does not have his car currently and he said that. He also mentioned that it was 106 degrees where he lives, and since he does not own a jet or a boat, his only other option is to walk. Walking in that heat is dangerous.
Also at eighteen, yes the parent no longer has financial obligations to that child, but if the parent sees that the child is having trouble on his/her own, then that parent should take initiative and try to help. On another note, I would not consider that to be mooching off at all. He's still part of the family, and once you turn eighteen, you shouldn't alienate yourself from your loved ones. If someone is taking me to dinner, they're the one who would be paying. If I were the one to be taking another person for dinner, then I would be the one who would be paying. If it was my first time meeting that person or we met recently, then we'd split the dinner bill in half. It's just formality.