Re: Cant see the problem
The problem is that if you have a target of finding 100 illegal immigrants and you can only locate 90, you will be tempted to go after some legal immigrants who happen to be, through no fault of their own, easy targets.
The Windrush people were asked to provide multiple pieces of evidence that they were here for each single year for over forty years. I don't know many people who could do that. I couldn't.
It's not unlike giving ATOS targets to find cheats and then finding that people were unjustly losing their benefits.