It has to be processed and formatted. The reporter uses a shorthand system that needs to dealt with, and you need to be able to figure out which party is which. Also, I'm pretty sure the reporter just blasts on through, so it would be difficult to distinguish between cases without some human intervention. You probably have hundreds of people getting arraigned in one session in the Bronx.

Digital audio can be more difficult. Automated transcription sucks, and the costs for human annoyed machine transcription are very high.