You are probably right that a major in economics is commonly used as a proxy to indicate interest in business. Indeed, there are many universities where the economics department and major are under the business division, rather than the arts and sciences division with the other social studies departments and majors. In some schools that have undergraduate economics but not undergraduate business, some of the elective courses in the economics department have a “business” emphasis (e.g. the accounting, finance, and business law courses at Claremont McKenna).