The interior design of the Model 3 is very simple - there are few physical controls - with the assumption that the car usually does not need to be driven by a human. As Elon presented it: https://youtu.be/GZm8ckvsu9I?t=2m2s.
Pure speculation: perhaps the simplified interior is necessary to bring the costs down for mass-production, and here is where the "synergy" with the autopilot comes in.
