(6) doesn't really work. Transplanting other person's hair works about as good as transplanting other person's liver - that is, it does work, but you are signing up for a life of disability on a immunosuppressant drugs. In case of liver when the alternative is death, it kinda makes sense, but being bald won't kill you. If that worked there would be absolutely no ethical concerns about it because it takes only a couple percents of a healthy person's hair "not to be bald" and no one will ever notice that amount of hair lacking on anyone. Typical transplant is ~1K follicles and it makes a great cosmetic effect, each follicle is 2-3 hairs and a healthy person has 100-150K hairs. One can probably take about 10x as many follicles from the back of one's skull without badly visible cosmetic effects and that could greatly improve lives of 10 people. Only if it worked.

I have no idea honestly if it's legally banned, and it probably depends on jurisdiction, but if it is, only reason is that "we should prevent people from screwing their lives up for reasons that stupid" and i totally agree with the ban.