Mostly because Europe is getting Africans who are there for free shit because they smell the West's weakness but have enough prejudice towards other african countries it stops any united fronts.

And carribeans in the case of the UK, it's the third generation that's the issue as the first and second generation embraced a British identity because it was a sign of superiority if they ever went back for a vacation.

It's also a lot harder to make brits want to guilt as much as Americans on slavery despite how hard they push it if you talk to the average person because:

1. They paid to free them
2. The used military force to stop it
3. If there was such a anger for it, why does the commonwealth exist?

It's why blm died quick in the UK and made no progress in any other European country.