It just says "detached garages with electric power" and a strict reading of 210.70(A)(2)(b) would say it is not required but I agree, if power is there, it is still a good idea. I would go with the motion detector too.
2011
(b) For dwelling units, attached garages, and detached
garages with electric power, at least one wall switch–
controlled lighting outlet shall be installed to provide illumination
on the exterior side of outdoor entrances or exits
with grade level access. A vehicle door in a garage shall not
be considered as an outdoor entrance or exit
exception
Exception to (A)(2)(a), (A)(2)(b), and (A)(2)(c): In hallways,
in stairways, and at outdoor entrances, remote, central,
or automatic control of lighting shall be permitted.
