That and also various principals are under the impression that DRM is possible, therefore they should implement it because it protects their IP, and protecting their IP is a fiduciary duty, therefore they must if they can.
That's not how copyright works. The copyright owners want to maximize earnings, and the licensees/distributors also want to maximize earnings -- they are typically for-profit businesses, and as such they have a fiduciary duty to maximize earnings. If they think that DRM will help them, they'll want DRM.
Of course for music DRM has proven to be pointless. People want to stream music, not buy music, and preserving media across so many media obsolenscence events has been such a pain that streaming is the only manageable solution for most people -- consumers don't want to make and manage copies anymore.
The same should apply to movies and such, but maybe not -- it's not clear yet.
This is not how corporate fiduciary duties work (courts repeatedly ruled there is no explicit responsibility to maximise profits or minimise taxes; Swedish Aktienbolaget are a notable exception there), though it is a common misinterpretation of them.
