Why is it okay to use botulinum toxin in Botox injections for both cosmetic and therapeutic reasons?

Botulinum toxin (e.g. Botox, Dysport) can be used successfully for dynamic wrinkles (e.g. forehead, crow's feet, smoker's lines, bunny lines etc), as well as for medical uses (e.g. hyperhidrosis/excessive sweating, migraines, TMJ pain, grinding and clenching, Raynaud's disease, cerebral palsy, club foot, bladder dysfunction, post-stroke spasticity and more). Botox/Dysport simply stops release of acetylcholine such that nerves can no longer (or greatly reduced) communicate with muscles, sweat glands, etc.

Cosmetic Botox is not covered by insurance and is commonly performed to help with forehead lines, frown lines and crows feet. Therapeutic Botox is covered by medicare and private insurance for medical reasons such as chronic migraines, spasticity following a stroke, cervical dystonia, hyperhydrosis, etc