I have long theorized that it is inscrutable for a reason: as a bar to laypeople reading a/o editing prescriptions.
Turning "30 pills of Pennicillin, refill 0 times" into "30 pills of OxyContin, refill 3 times" is much harder when you can't even figure out which part is the drug name.
(Kids who are about to point out this couldn't work: Prescriptions used to be hand-written on paper, and never checked by the then-inexistent interwebs.)
I know of someone who was let go from an employer when they contacted the doctor’s office whose stationary was used on the employee's many absence excuse notes. It turned out they were a gerontology office. The employee was in their early twenties.
Controlling access to stationary, prescription pads, and the office’s fax machine is one part. Making it hard to forge the doctor’s handwriting is another.