They should be taxed the same. As an added bonus, that would make the Tax Code a lot simpler because from an economic standpoint, interest and dividends and capital gains are all the same thing, and so the Tax Code has to go on for pages and pages trying to define which is which in a veritable galaxy of various transactions with only mixed success, so the courts have to decide which is which when clever tax lawyers try to manipulate transactions to convert ordinary income into capital gains. It does help enrich tax lawyers however.