I'm a nerd by trade (programmer), the senior staff here take turns being on call for serious issues like a release that is destroying user data or bricking their phones. Typically it means one 9-5 period, and one 5-9 period during each Monday-Friday week, and one weekend each month.

The requirements are "be near a laptop with internet connection in < 10 minutes if an alarm goes off, and don't get too drunk to do your job". It's limited to senior staff with > 1 year of experience working on the product. It's those of us responsible for things like infrastructure planning, hiring, and code reviews so it encourages us to make sure we set policies that prevent us from being disturbed in the evenings. Stability is good for both us and our users so our goals are aligned.

While I'm not compensated for the rare time I have to work 'extra' hours I work (nor the fact that I can't smoke a bunch of crack in the woods on a Wednesday night), my base salary is fair for a person with the level of experience and responsibility that I have. I'm salaried so taking the a day off here or there isn't really a problem and nobody bothers to track those either. I don't feel abused or unfairly treated at all.

I don't think I'd like a union, especially if it were something like the ones in films where working with 'non-union' people is difficult or impossible. While I appreciate that some people would like a union and that there may be a case for a 'professional society' for computer programmers, I hesitate to endorse anything with mandatory or near-mandatory compliance. While not perfect, in many ways computer-related fields are more of a meritocracy than others. I'm pretty good at what I do and I'd hate to see my ability to make a living compromised without leaving me the choice to opt-out.