the thing about the methods, LM is the easiest to get into ie for cost and training, produce "moderate to exceptional" visual improvements, and the least potential for creating "damage".
Hot water extraction costs the most if you're going to buy decent equipment, requires a high level of proficiency in training, and depending on that training, if poor will produce poor to moderate results and potential for great damage, to exceptional to remarkable cleaning when having a high proficiency.
Its like playing a violin, the same instrument produces the most God aweful sounds or the most amazingly beautiful music. LM is more like playing a kazoo. Hard to mess up.
It would be extremely hard to produce a standard that could be "controlled", regulated. The best you could do is what the CRI tried and failed to do, regulate the equipment and the chemistry. They just made a mockery of the testing. The
IICRC tries to train the technician, ie the user, which is the better way to proceed. With a well trained tech, they can use any piece of equipment, any method, and can safely use or even more important, know what not to use.
If the govt got involved they would create a mess, it would become more corrupt, there would be more bait and switch because the "good cleaners" would be regulated out of busn. That, and LM methods would be more highly regulated because of their limited means of actually "cleaning".