Racism and all the contortions racists go through to try and justify it.
There's a significant Kurdish population in my nearest city, nearly all of whom came here as asylum seekers. One of my friends is Kurdish and arrived here, not on an inflatable boat, but in the boot of a car.
I've met several of her Kurdish friends, all of whom fled persecution in their home countries and came to the UK. The Home Office clearly recognised that Kurds are a persecuted group in their home countries and they all got refugee status without any hassle.
I've never heard of any of them experiencing racial abuse or discrimination in the way that recent migrants from Africa and Asia seem to, and I'm starting to come to the conclusion that it's because they have pale skin and don't look "foreign".