Because they are professionals who know what they are talking about.
They carefully recounting what they know and saying they can't comment on what they don't know.
Imagine that. The GOP lawyer attack dog looks to be very nervous. His voice is very shaky very stacco very rigidly doggedly strident. I wonder how this is going to enhance or destroy his career? Not coming across as being confident assured knowledgeable calm intelligent and proficient. Poor guy. He musta got the short straw.