Why? Because many of us have experience with the bad side of unions and we don't want to see programming become anything like that.

You'll end up with mountains of regulations and specialties and not be allowed do anything outside of those bounds. Imagine being told "you're a front end programmer. You are not allowed to submit code for the back end, that is for certified backend programmers only. Also you are not allowed to edit CSS or HTML. That is for certified web designers only" Why? Because that threatens the backend guys and web designers jobs). Check out some union rules sometime and look at all the crap. I don't want any part of that to come to programming