George Carey isn't promoting the notion that all Mexicans are rapists and thieves or that all Muslims are terrorists. That's the difference!
Unless anyone lives in a country,they can't see the daily news or the hidden crime that people living there read and see.
People from abroad who come to this country flock to Liverpool to see its shipping and music heritage,but they don't read the daily news on the place which is full of crime/murders/shootings,do they ? So these visitors don't have the same insight of a place as residents do. The same as George Carey doesn't have any idea of the criminals from Mexico infiltrating the USA. Genuine people follow the rules and instructions before entering a country,without having to shin over fences,etc,or whatever other means they unlawfully use.
You always have to elaborate by inferring to " all " and it isn't that way. We have murders/rapes and theft in this country,but I wouldn't refer or blame it "all" on immigrants/refugees. We have enough of our " home-grown " criminals.