It's easy to tell who the criminal migrants are when they commit crimes in the UK such as the Eritrean rapist of a minor English girl. He wasn't deported because he wouldn't receive adequate treatment for his PTSD if returned to Eritrea and would likely be in trouble with the authorities in Eritrea because he dodged compulsory service ...cry me a river.

Oh, and when you look for his name, you won't find it because his identity is hidden in order to protect him. Yet UK citizens who post anti immigration memes on facebook are named, shamed and charged.
This is a legal issue. That is, the reasons why someone might be given leave to stay. For example, some people have been allowed to stay because they're gay, or transgender, and it's not accepted in their home country. Do you think that's right? I mean, it's debatable at least, no?
But the law simply states: [a person is]
"unable to live safely in any area of their home or country of origin, due to a well-founded fear of persecution."
The broad topics of said persecution are: Race, Religion, Nationality, Political opinion, and "anything else that puts you at risk because of the social, cultural, religious or political situation in your country, for example, your gender, gender identity or sexual orientation,"
It is no wonder it takes the government a long time to decide these things. The criteria is quite vague.
These types of laws are at the root of the problem.
Yet UK citizens who post anti immigration memes on facebook are named, shamed and charged.
Well, from the ones I've seen, they're usually posted by pig-ignorant animals who think spreading hate and instigating violence is their right. Sorry to be so blunt, but the ones I've seen (clearly I've not seen them all) are just hate-mongers pretending to be patriots.