Stay at home mums (and others) and photography as a profession

[WhoDo]

why do photographers get hung up on the term "professional photography"

Probably because of a lack of a common understanding of the term. Here is what the Free Online Dictionary says:

pro·fes·sion·al (pr-fsh-nl)
adj.
1.
a. Of, relating to, engaged in, or suitable for a profession: lawyers, doctors, and other professional people.
b. Conforming to the standards of a profession: professional behavior.
2. Engaging in a given activity as a source of livelihood or as a career: a professional writer.
3. Performed by persons receiving pay: professional football.
4. Having or showing great skill; expert: a professional repair job.
n.
1. A person following a profession, especially a learned profession.
2. One who earns a living in a given or implied occupation: hired a professional to decorate the house.
3. A skilled practitioner; an expert.

Among the adjectival uses (descriptive use of the term) some here are applying definition adj 1b, some definition adj 2/3 and others definition adj 4. Frankly I prefer to use definition adj 4 when referring to the output of respected photographers (definition n 3), and definition adj 2/3 when referring to those who have simply "hung up a shingle" and invested financially in following the profession (definition n. 2). Definitions adj 1a and n 1 are of little relevance in this discussion of the OP's original question since they relate principally to academic qualifications and standards.

So before anyone starts arguing the toss about who or what is or isn't "professional", I suggest you start with a common understanding of what you mean when you use the term.

In referring to the OP's post, SAHM's (and others) may fit definitions n 1 and n 2 without coming within a bull's roar of definition n 3! Certainly that former class of "professional" doesn't appear to be bound in any way by the requirements of definition adj 1b (i.e. conforming to professional standards), and that is the horns of the dilemma for those who truly love, invest personally in and value their profession well beyond its capacity to earn them an income. That very passion and personal investment prevents "getting over it (sic)" when those whose only commitment is financial give the industry a black eye.

Some sections of the market now see photographers in general, particularly those doing weddings and portraiture, as little better than used car salesmen and that is very distressing to those who have put in so much time and effort to elevate the industry's standards toward expert performance (adj 4) and away from simply earning an income (adj 3).

I hope I have made my point clear, despite the many references.