If resistance to occupation was more difficult to deal with, it might matter more.
Occupying the Soviet Union just to the Urals should be an immense drain on the German army. Occupying New England, New York, and a strip of land to Ohio should also be a significant drain on any Axis power.
And occupations themselves are very profitable, further making it a pointless pain to drag out surrender in the case of either the Soviet Union or America.
Washington DC to New Orleans is 1554.792 km as the crow flies. Brest to Moscow is 994.701 km as the crow flies. Washington DC to Los Angeles is 3940.157 km, over two mountain ranges that dwarf the Urals.
It should be incredibly difficult, to the highest factor, for an Axis player to capitulate the US, particularly with an overseas supply line.