All those Euro and Mediterranean countries have not been exposed to the civil rights movement we have so they are still in the dark (no pun) with alot of these racist issues. The funny shit is Italian people look down on Sicilians due to Sicilly being mutted out due to other cutlures (Moors, Phoenicians, Greeks,etc), it's some xenophobia between the countries.
It's just basic human nature shit, you are more comfortable with what looks like you and instead of learning to judge people individually they become racist. Then you have cultural norms that cause future seperation.
With all that said, there are good and bad people from every fucking culture, all that broad generalization is stupid. You have Spanish people who have biases against other Spanish (Puerto Ricans vs Columbians) or even (Jamaicans vs Haitians).