Power
You have the power to make some serious screw-ups on medical records. That can be plain-old dangerous. Doctors dictate medicines they prescribe and any side effects or drug interactions. It could be life threatening if you type 100 mcg instead of 10 mcg.
As a transcriptionist, you're also privy to some pretty sensitive medical information. You'll hear all about someone's medical issues and maybe their psychological problems as well (if you're doing transcription in the mental health field). This information can be pretty damaging if it gets out.