This is a very simple problem and racism has almost nothing to do with it:
White founder has a business idea and they bring along their friends - most likely white. Those friends bring in their friends and colleagues - also most likely white - to become the executive team. The executives hire tomorrow's managers. By that time the vast majority of employees are white, and even if they work very very hard to hire black people, it will take a very very long time until there is proportional representation all the way up to the executive level. Some execs work well into their 80s, meaning that it could take more than a century until there is population-proportional diversity at any predominantly white-founded institution.
The longer a lack of diversity persists in a company's trajectory the harder it becomes to fix it. The only solution I can think of is for black people to start more companies themselves.
Those are huge companies with tons of cash. Referrals are less important when thousands of college graduates are stampeding for a job at a tech titan. Also, how much of the upper management at either is Indian or Chinese?
White founder has a business idea and they bring along their friends - most likely white. Those friends bring in their friends and colleagues - also most likely white - to become the executive team. The executives hire tomorrow's managers. By that time the vast majority of employees are white, and even if they work very very hard to hire black people, it will take a very very long time until there is proportional representation all the way up to the executive level. Some execs work well into their 80s, meaning that it could take more than a century until there is population-proportional diversity at any predominantly white-founded institution.
The longer a lack of diversity persists in a company's trajectory the harder it becomes to fix it. The only solution I can think of is for black people to start more companies themselves.