It appears the box location is a LOCAL spec and not part of the NEC.

Found this for WELD county from their Building and Planning Dept. (Entire article here )
The electrical service disconnecting means containing overcurrent protection (main breaker panel) may be located inside the home at a readily accessible location if the service disconnecting means is placed back-to-back with the metering equipment and the total service conductor length does not exceed 3 ½ feet measured from the exterior wall of the home. The service disconnecting means shall also be located on the ground level. [29.2.70A, Weld County Code]