I have had a successful career in electronics and software, working for companies at the leading edge in their fields. Only once have I been asked to produce my certificates and that was at an interview for a job which it turned out I didn't want once I learned more about it. I have voted with my feet when I felt my abilities weren't appreciated or sufficiently remunerated. I have been headhunted and also found jobs via social networking (no, not on the internet - in real life). I have been laid off 3 times - a risk of working for small enterprising companies with more enthusiasm than management ability - but I don't regret any of the jobs I've been employed to do. I must mention here a person I have worked with who had far more letters after his name (Microsoft Certified, etc.) than I, who was as much use as a chocolate teapot. Because he'd been on the official courses and got the certificates, he knew he was right (even when he was wrong).
I was a member of a union once - the Students Union - which was mandatory at British Unversities when I was a student - and I've never joined one since. My view of unions is that they're fine for workers who may be tied to a job through geography, tradition, family or other factors which prevent mobility. I have also found more than one incompetent management team which resulted in workers being laid off (myself included) but in these cases, (i.e. no money and no jobs) what good could a union do? The concept of a union is excellent; unfortunately, all too often the union proves as problematic as bad management. So my final vote is NO to a union for IT workers.