Brendan McMurtry-Howlett - Thought #3 - Does it Count as Diverse Casting?

So the thought today comes after a conversation with a friend of mine, a fellow artist who was telling me about working on a show that required him to use a British accent. He was working with the production's dialect coach and was given a bunch of audio samples of British dialects for him to learn. Now my friend is person of colour, and actually, his family is from England with deep roots in Jamaica. But here he is listening to all of these audio clips that had been brought to him, these sounds and dialects that he was being asked to replicate, and every single person on these audio clips was white. And he said to the dialect coach, well, aren't there any black British people that I could use as samples? And the dialect coach had never even thought about that possibility. So this brings me to my thought: does it really count as diverse casting if people of colour are being hired and then are essentially asked to play white people? P.S. If you haven't seen The Shipment by Young Jean Lee's Theatre Company you should definitely do so right here: http://youngjeanlee.org/work/the-shipment/