That is actually not correct. GMRS licensees routinely use 5w on many
FRS frequencies. See http://www.gmrsweb.com/gmrsinter.html

No, GMRS uses 5W on GMRS frequencies that happen to be
SHARED with FRS. The radios that cover both the GMRS unique
and FRS unique frequencies will ONLY use FRS power levels on
the FRS unique frequencies.

Mike