Remember that most of Europe is north of most of the US, so there is a major
daylength difference.

I don't think that accounts for it. New England is pretty close to the latitude
of much of Europe. I think the main difference is the Gulf Stream. The
northeast US has more extremes of temperature and weather than western Europe.
Eastern Europe & the Caucasus have a more severe climate. Foliage color is a
byproduct of sugar storage. There is evolutionary pressure for trees in a
severe climate to store more sugar for the winter, hence the fall color.
However, that does not explain why Acer platanoides in the northern US lacks
fall color, while the same species on the other side of the world in a similar
climate has nice colors. That's why I want someone to transplant those trees
from the Caucasus. Since Norway maple already has numerous traits which make it
popular, nice fall color would be an additional selling point. Look at the
popularity of 'Crimson King.' The only danger is that if they are attacked by
some new plague, the devastation would equal what we had from Dutch elm
disease.
Iris,
Central NY, Zone 5a, Sunset Zone 40
"When you come to a fork in the road, take it." Yogi Berra