Because its true. Certain people do certain things.
Who tarmaced the UK and put most of the drains in?
I think this is stupid and I'm far from being a liberal PC snowflake. I'd hire someone based on how they come across when I meet them. I wouldn't not hire any particular race or religion or nationality because I don't have preconceptions about them. Of course you go with your gut instinct on most people but whose stupid enough to categorise it in such a way. It's almost as though the OP has a tick box in his head - ''need a plasterer? Right - got to be jamacian!''