We do use folk instruments in elementary music -- largely percussion--and from different cultures. Concertinas and the like are not offered because they aren't found in a marching band, a concert band or an orchestra. Even kids who play guitar are out of the main stream music ed fields--except an occasional electric guitar or bass that can play jazz. Our school just cut funding for the marching band so the parents are left to figure out how to raise 30,000$ -- at least they didn't cut band, chorus, or strings. Unfortunately the budget does not allow for replacement instruments etc. that are needed so again it's back to the parents.