The nerds at Ma Bell used to provide very high quality telephony; they were shocked and appalled when the market chose low quality low cost telephony. The medical transcription market has gone through the same change..
The documents, especially the ones used clinically, can suffer from lower quality of ASR and/or offshoring.. Also, in the old days, light editing was usually part of the process. This happens less in today's price obsessed market and sadly results in less readable reports.
On the other hand, today it's possible to get turn around times of 0 with document issues identified in real time by NLP. That is a really big improvement. (I don't know if Nuance has that, but if they don't, they will soon)