From my perspective, comparing genealogy as it is practiced to the law profession is entirely inappropriate. In fact, finding a clear analogy between any licensed profession and genealogical researchers takes a great deal of fact stretching. The closest activities where I find a basis for comparison are real estate appraisers and property and business valuations. In both those fields, the appraiser or valuator gives a personal opinion based on research or personal experience. You can either believe what the appraiser says or not. But in the case of a real estate appraisal, you may or may not get a loan to buy the real estate based on the appraisal.
In genealogy, a professional does research and gives you an opinion. You may or may not accept or like the opinion and you may think you have been overcharged. But there are no other monetary implications to the opinion. You do not lose a sale. You do not have to pay a higher price for a piece of property. You do not have a loan application declined. You can throw the opinion of the genealogist in the garbage and ignore it with total impunity.
Real Estate Appraisers are licensed at differing levels and with different results in each of the U.S. states. However, in many states, you do not have to have a license to give an appraisal except for federally related transactions. Most appraisals are based on the research and the experience of the appraiser rather than the existence or non-existence of a license. In some states, anyone with a real estate license can sell real estate. At least in Arizona, by law, anyone who owns property can testify in court as to the value of the property the own. Equally, in Arizona, any can sell their own property, although access to professional online tools, such as the Multiple Listing Service, are limited to certain licensed professional real estate salespeople. In most of the U.S. the term "Realtor" when used with the sale of real estate is a trademark and limited to licensed Realtors.
Now, I said that most of the attempts (all?) at using other types of licensed business practices as analogous to genealogy is a stretch. As I pointed out above, the main factors for this difference lie in the use of the work product of the licensed professional. Some so-called professional licensing schemes in the U.S. are nothing more than revenue enhancement. They are simply a tax on the right to do business. At the other end of the spectrum are such professions as lawyers and medical doctors where there are very specific and extensive sets of rules that govern their actions and practice and where there are formal boards or in the case of attorneys, a bar association, that enforces those rules and practices. Denial of a license to practice, essentially bars a person from the profession. Except for some extremely limited circumstances, if you are not a licensed attorney, you cannot represent a client in court. Period. This is enforced by rules passed by the Arizona Supreme Court and binding on every other court in the state. Are there exceptions? Of course. But they are reviewed on a case-by-case basis by the regulatory authorities who happen to be judges in the state court system.
You might question why this type of system exists and why it is necessary, but such questions are simply ignored by the licensing authorities. Any such arguments immediately get into the area of competency, educational background and accountability. One good way to get a perspective on professional licensing is to read the list of censored and disbarred attorneys printed in the Arizona Bar Journal every month.
Now, is there some ground or reason for imposing such a regulatory structure on the genealogical community (however that is defined)? First of all, there is only a tiny professional genealogical community in Arizona (or anywhere else for that matter) whereas, in Arizona alone, there are somewhere between 20,000 and 30,000 licensed attorneys. Yes, you read that right. My best guess is that there are far less than 100 practicing "professional genealogists" in the State of Arizona. The Association of Professional Genealogists advertises that they have somewhat less than 2000 members in the entire United States. I would think that the professional genealogists are highly concentrated in the larger population areas and especially in New York, Washington D.C. and Utah.
There is no easy way to determine how many people practice genealogy and of that number, how many are charging a fee for doing research for others. Of the number who may have been paid for their services from time to time, I would guess that the number who actually make their living as professional genealogists to be a much smaller number, especially if you discount all those who are professionals who work for libraries, repositories and other online databases and aren't doing "research for hire."
From this standpoint alone, talking about licensing genealogy is inappropriate (I might say ridiculous, but I didn't). Why bother? If someone wants to go through the process of certification from one of the two major boards who do that sort of thing, more power to them. If they want to join the Association of Professional Genealogists, go at it. But leave the rest of us alone. If any kind of professional, licensed or unlicensed, breaches their employment contract (whether or not a written one exists) there are ample remedies in court for breach of contract, fraud, misrepresentation, theft, or negligence.
From my perspective, there are no persuasive arguments for any kind of governmental regulation of genealogists at any level of activity, simply from the standpoint of the number of participants. Do we really need another government bureaucracy to regulate genealogy? I think not.