I don't think women of any ethnicity can claim to get more dances or not get enough dances in the USA.
I have verbalized like it several times and also mentioned a few times how I hardly encountered followers with African roots in EU.
So if blacks in europe prefer asking white women while in the US this is not the case, then maybe the cause might lie in them feeling different. Blacks in the US are there since centuries so they feel rooted in the US, while in europe they came only the last decades so they may feel still unwanted by many and seek more alignment / more self-affirmation? But this is really speculation.
At least in France there are equally black females as black males, so you can't explain it with ratio being different in the country.