Engineers, Lawyers and Doctors have professional associations rather than unions. Arguably, this is what software engineer should have. The American Medical Association (AMA) is extraordinarily influential.
Edit: one could argue the difference between a professional association and a union is a matter of degrees. A professional association certainly seems an easier sell. Possibly a professional association with aspects of a union could be considered.
All of those professional associations were enshrined with their exclusive rights by law. We live in a democracy, and the law is at least nominally enacted for the public good. The case for requiring professional licensure was that it would protect the public from unqualified practitioners, and it would allow bad apples to be held to account.
If you want a professional association like engineers, lawyers or doctors, it needs to have a clear public benefit. Benefiting software developers is not enough. That is one of the important differences between a professional association and a union.
Disclosure: I am a licenced professional engineer (software).
If you want a professional association like engineers, lawyers or doctors, it needs to have a clear public benefit. Benefiting software developers is not enough. That is one of the important differences between a professional association and a union.
I think in practice, the line is much fuzzier than you describe. Union rights are also written into law with the implication that they benefit society directly and indirectly. An electricians' union at least ostensibly benefits society through making certain qualified people engage in electrical work and even having qualified medical attendants has obvious benefits.
Of course, one can point to huge potential benefits to society from making certain that various sorts of software is constructed correctly so the case for a professional software engineers' association isn't that hard.
Why wouldn't you want a contract with your employer? Top executives have contracts and professional athletes have contracts. My contract is I can be fired at any time for any reason, or no reason.
Most of those that you mentioned are considered professions that require some sort of specialized training and/or board certification with some sort of oversight body. While they don't engage in collective bargaining, they do serve to control who is allowed to practice a given profession, thereby limiting the pool of qualified individuals.
While different from a union, these professional bodies serve some of the same functions in the end (raising wages, establishing standards, etc.)
In Alberta, Canada, professional engineers are barred from joining unions. While not universal, it is quite common for provincial engineering associations to bar their members from joining unions. Engineers are also exempt from many labour law protections (overtime, minimum wage, vacation time, etc.). Needless to say, I am not exactly happy with the current state of affairs.
Edit: one could argue the difference between a professional association and a union is a matter of degrees. A professional association certainly seems an easier sell. Possibly a professional association with aspects of a union could be considered.