Staying in the office is more convenient and productive for practitioner and staff. No travelling time or agents fees. No increased risk of oversight. No increased risk of disputes. Can make detailed file notes of what was checked and changes agreed on the spot.
Sight is a more powerful sense than hearing.
The telephone is a barrier to communication. The physical presence of the counterparts prompts more effective comparison. You have to take more on trust. Faster is not always better. Current time to exchange is not unnecessarily slow.