A) In restaurants, more adults eat more often, at least 30+. Also, there are more often people who hold high positions, are sociable, have a couple, who love gourmet dishes, aesthetes (if we mean a restaurant that is not related to fast food and catering) In front of the TV, freelancers, students, lonely people, in general, those people for whom the atmosphere and service do not matter, most often eat.
B) tips are left by mature people with a certain status in society, educated (in terms of secular etiquette), grateful Too much is eaten first of all by those people who have at this time, also single people, people who are going through a difficult life stage (depression, stress) In my opinion, people smoke in most cases, who have a busy schedule, difficult work in moral or psychological terms, or the opposite of those named - people who smoke from boredom, stress, etc.
C) when a person has more money than is vitally necessary (this is very individual), he ceases to spare money by giving it free of charge. This is how charity is born. Just like that, I would give money to a graduate of Brooklyn College, as this would obviously make more sense, help the person more. But if a successful graduate proposed a business plan for which investment was needed, and I liked it, then I would certainly choose the best project, in my opinion, for investment, regardless of the place of study of its creator