TRW, in this case, is a cascading infinity of corporate law, tax law, accounting practices, jurisdictions, lobbyists, parliaments and special interests. None of these exist in economist's models, unless they're modeling public choice theory or somesuch.
Capital gains is just as gameable as corporate income, in practice... and more politically explosive.
IMO, if there is an actual interest in taxing wealth, just tax wealth. Assume 5%-8% return on wealth, and tax total wealth on this basis.
Both succeed/fail in the same way, marking to market. Apple Inc, the publicly traded entity, is able to deny its income for tax purposes (they say they paid this money to an irish subsidiary), while claiming it on behalf of their shareholders. The CGT version of this is unrealised gains.