Blackfacing is considered racist in america due to historical reasons with white people mocking them. In Europe, it is not really big deal as we do not have that historical burden. Same way as black people in common language are called "neeger" (direct translation from nigger) here, without everyone being racist.
We had similar case just recently here, we have a very popular tv show "Your face sounds familiar" here, where famous musicians and actors make parodies of different artists. It is quite common to turn someone "black" if you actually make a parody of a black person. One of the performers this season dared to post backstage photo of herself to instagram and it went viral with massive amounts of random people suddenly starting to spam him for being racist.