How much class G is there really in the USA ? (genuine question), because my quick searching indicates that it is mostly at very low levels (around 1200' AGL) with class E above.
ie. there is little need to mark frequency boundaries because it's either class E or whatever ATC tells you.
Here, we need the frequency boundaries because our class E generally starts at the higher altitudes so we need to know where the G/E boundary is.
and no, I do NOT want the class-E-everywhere war to restart)