When you look closely at PROFESSIONS (sometimes called "the learned professions"), there are a number of things that stand out.
Professions have a large body of esoteric knowledge, not known to the general public, which must be mastered in order to practice the Profession. And that knowledge is formally TESTED before one can practice in the Profession. If you don't pass the test, you CANNOT practice the Profession. For example, law, medicine, architecture, dentistry. Professionals must MAINTAIN their current knowledge of developments within the profession, usually through attending annual classes throughout their careers. This obligation never ends, as long as you want to retain your license.
Professions are self-regulated, and not controlled by the state. The Professional Associations are formed FOR THE BENEFIT OF THE PUBLIC, and not for the benefit of the practitioners. They guarantee TO THE PUBLIC that practitioners are competent, ethical, and up to date. The State can't make you a lawyer. Only the Bar Association can admit you to the practice of law. Same for medicine, professional accounting, professional engineering, and so forth. Obtaining a state license is NOT the same as entry into a Profession.
A professional can "hang up a shingle," and work as an independent entity. Although they sometimes work for a company or a government agency, their membership in the Profession is independent of that employment; they must keep their membership current and their education up to date. If they don't, they will lose their Professional license, and probably that job as well.
As for professional conduct and performing one's professional obligations, Professionals are held to a higher standard than anyone else. Most people who are sued for malfeasance "on the job" are held to a NEGLIGENCE standard - is the act or omission something that a reasonable person would have done or declined to do? A MALPRACTICE standard requires that a Professional conduct himself according to the CURRENT state of the professional art. He must know the latest laws and applicable court decisions, a doctor must know about pharmaceuticals, procedures, and diseases that may not even have existed when he graduated from Med school. A CPA must know the latest tax laws to the minute. It is a much higher standard than any non-Professional practitioner.
A Professional can be disbarred - prevented from working in the Profession - for malfeasance that does not rise to criminality. Improper accounting, for example.
In summary, there are not many professions. Law and medicine, obviously. Architecture. And when an accountant or an engineer chooses to be come a professional, he must meet educational standards, ethical standards, pass one hell of a test, and maintain professional competence throughout his career as a professional.
So, what about Teachers?
There is no objective body of knowledge about teaching that must be mastered. Teaching methods are in fact infinite in number, some successful and some not, and nobody is keeping track. Nor are teachers required to DEMONSTRATE any particular level of competence in their area of teaching expertise. (A semester of "student teaching"? Are you kidding?). Usually a certain number of college credits is sufficient, even in STEM areas, where you would expect competence to be absolutely mandatory.
There is no professional teaching organization that works to benefit the public, or guarantees that teachers are competent, ethical, or up to date. On the contrary, the major teaching organizations are akin to LABOR UNIONS, which function EXCLUSIVELY for the benefit of TEACHERS, and one could strongly argue, AGAINST THE BENEFIT OF THE PUBLIC, by protecting lazy or incompetent teachers from ruin.
Teachers are NEVER held to a "malpractice" standard. Indeed, the very idea is laughable. ("My son can't do quadratic equations! I demand that the math teacher be dis-BARred!") They are not even held to a "negligence" standard, and can remain on the job year after year, leaving failure in their wake until their early retirement.
I think you get the idea. Teaching is NOT a Profession. Period. Many teachers display great "professionalism," in doing their work, but the sad fact is that such a standard is not required, and many teachers fall far short of that mark. Ironically, it is when teachers (and their representatives) are acting in the LEAST Professional manner (demanding more money and benefits for less work, year after year) that they DEMAND to be treated AND PAID as "professionals."
It is nauseating. A Good Teacher is a BLESSING to society, but Good Teachers don't have to DEMAND to be treated with respect; they just get it.