Comfort and Convenience
Cabin temperature is a matter of personal preference rather than a setting with one correct value. People differ in clothing, circulation and tolerance for airflow, so passengers sharing a single cabin often want slightly different conditions.
Safety and Driver Assistance
Familiarity with controls is easiest to build while stationary. A few minutes spent identifying the gear selector's positions, the light stalk and the demisting buttons means less improvisation later, especially in an unfamiliar or recently acquired car.
Multimedia and Connectivity
Calls are the part of phone use that matters most in traffic, since answering by hand is awkward and legally restricted. Where hands-free telephony is available, the practical gain is keeping conversation and driving separate.