I can try to dissuade my boss from putting in the 33rd analytics gizmo on our site, but they are remembering the sales pitch and all that lovely data. If I say no they'll ask someone else in the office, few more times I'll be needing a new job.
It's interesting you mention doctors and engineers, two professions that have more accountability and two well subscribed professional bodies. If doctors were being asked to surveil patients or report something, as governments will occasionally suggest, the BMA will shout rather loudly. The press listen, write up a piece with suitably scary headline, and the govt changes mind (usually).
The IET (UK Engineering body) has double the global membership of the BCS (computing) which is in far more countries. I'm going to hazard a guess there's more in tech than engineering.
I'm not aware of any tech or professional bodies that attract anything but a tiny minority. We can't blacken the web like the Googles and Facebooks can in the face of stupidity like SOPA. Without some group body we're left with signing change.org and blogging. If we don't take a job there's millions who will - FB and Google are in the top 5 best places to work, yet are part of the problem.