It is important that your S understand that economics and and undergraduate b-school are very different paths. A number of schools on your son’s list do not have undergraduate b-schools.
Economics is a liberal arts course of study and gets very theoretical at the upper levels. In contrast if he goes to an undergraduate business school your S will take a business core with introductory classes in subjects such as accounting, finance, IT, marketing etc. and then he will major in one of those disciplines.
I’m not saying that one path is better than the other, but they are different. I would strongly recommend that your S take the time to look at the coursework (can be found online) for both undergrad b-school student and an economics major, see if one path is preferable, and apply accordingly.