Every tech company could meet their diversity goals tomorrow if they had a good training program. Your “very selective” (read: White, Indian, Asian) hires aren’t that great to begin with. Why not invest in underrepresented communities?
Because it’s more convenient not to and because the job market discourages it. Training costs time and money in a world where developers rapidly shift between employers. The assumption is that job candidates are trained by a prior employer and fully ready to execute the work of the current employer, which is a fallacy of preferential bias.
Other industries solve for these problems by mandating training as part licensing programs either through broker/agent relationships or through internship/residency programs.
Most companies don't have any diversity goals (if you mean gender, color, age, ...) and I assume that those that do, they do it mainly for political reasons.
Just hiring people of different color or gender doesn't increase the success of a business. So why would it be a priority? Businesses typically only need people who will get the job done, no matter who they are.
Why companies don't have training programs is another (good) question.
Other industries solve for these problems by mandating training as part licensing programs either through broker/agent relationships or through internship/residency programs.