To drive an automobile, you must pass several tests before you're issued a license. There is the eye test, the written test, and then the practical driving test. In some states, young drivers are encouraged to take a driving course while in high school to get a learner's permit. As one ages, states may require an older driver to take another eye exam and sometimes a practical exam to maintain licensure, and a doctor can recommend that an elderly driver not be issued a license.
As a therapist ages, there is no mandated eye exam, written or practical testing and mental capacity exam to maintain licensure. All a therapist has to do to keep his license current is take the mandatory CEUs every year dictated by the state and he could theoretically practice until he dies. Why don't state boards have a retirement age for "old" therapists? Police officers and those in the armed services have a retirement cut-off and for some positions a person isn't eligible to apply if he's more than 35 years of age. Technically, a person who is 75 years old could become a new grad PT or PTA.
As we get older, we may not recognize the limitations we have, whether they are mental or physical. A 98-year-old therapist may not be the best person to treat a heavily involved CVA patient but since he has a license to practice, he can legally provide care for that patient even if that treatment would put the patient in harm's way. And who am I to tell the elderly therapist not to see certain patients since the state board is who issued the license to practice therapy in the first place?
I won't get into the legal complications state boards will have to justify issuing licenses to therapists who score less on a Tinetti and Berg than their patients and get the Mini Mental exam completely wrong. But all it would take is one good lawsuit and an internal investigation to ask pertinent questions like, "Why did the state issue a therapy license to a therapist who has dementia?" and "Who allowed a therapist to treat patients when he is barely functional trying to instruct others in ADLs and safety?"
Since there's no current oversight on when a therapist has to retire and no doctor can recommend that our therapy license be suspended, we could treat patients forever and ever. Imagine if your loved one is safer, more limber, and has a better gait pattern than your therapist while in the nursing home -- maybe then changes will occur.