Doesn't answer your question, but I'd imagine a third motive for supporting these things (when they already exist but are gathering support) is just optics. If

Doesn't answer your question, but I'd imagine a third motive for supporting these things (when they already exist but are gathering support) is just optics. If your in the public eye, would you rather be seen as pro-terrorist/anti-children, or anti-privacy. The latter seems to generate less anger, so the choice for many career politicians is obvious.