// White [voice] actors need not apply for jobs that require voices representing those of ethnic minorities. //
That is very different from what you wrote in your question.
The problem is miscasting. What is the point of employing someone to fake an Indian, English, Mexican or French accent, when there are plenty of actors from those cultures who can make a better job of doing a more authentic and believable performance ?
Sean Connery playing an Irishman is miscast. The bad acting distracts from an otherwise good film. It might sound passable to Americans, but ludicrous to the rest of the world.
Comedy accents are often are very funny, but there is a point where they become derogatory to the cultures being portrayed. Most of Peter Sellers’ accents are funny, but his upper class Englishman, German megalomaniac, or inept French Detective, have a laughing at foreigners vibe to them.