There has been an explosion of "cosmetic medicine" over the past few years, and many Physicians are being approached to "increase their bottom line" by entering into this lucrative field.
There is a tendency for the public, and some in the profession, to view laser treatments, Botox and cosmetic filler injections as cosmetic rather than medical treatments. The use of prescriptive drugs and devices, however, is the practice of medicine, and the same laws and regulations apply to these types of treatments as those driven by medical necessity.
Cosmetic procedures are the practice of medicine, and Physicians are responsible for their patients, regardless of who performs the treatments. There is no legal scheme that allows Physicians to collect a fee for signing their name to an agreement to lend their license to an entity to practice Medicine.
Legally, the "clients" of the spa or salon are patients - the Physician's patients, and that arrangement comes with all of the responsibility and liability that goes with any other Doctor-patient relationship.
See the entire Medical Board of California article here: http://www.mbc.ca.gov/licensee/medical_spas-business.pdf