Also hiring is often based on trust and networks. People refer others to their company and jobs. That trust tends to work out pretty well for companies. If people get laid off they tell their friends and their friends pass on opportunities to them or try to help them find new jobs. And people tend to make friends with others they share a culture and language with.
If you add a bunch of barriers to make companies have to hire proportional amounts of every ethnicity or culture, that slows down hiring and can be an extra regulatory burden for what reason?