Academia is 1. costly, 2. long, and 3. weighted to favor people from backgrounds that can afford tutors or finishing schools. You want Ph.D.s from non-elite backgrounds with the financial means to handle 10 years of college at a poverty wage (or for the first 4 years, who can pay large sums rather than earn anything.) Plus, when they finish, they’ll be expected to have picked up the habits that will impress other faculty, who are disproportionately likely to come from families where Ivy League colleges are realistic options. How big can that pool possibly be? And the timeline to increase the pool is decades long.
Industry can be similar, but at least there you have the option for a smart kid to go through a bootcamp and move their way up on merit, while making a competitive wage. The pool of DEI candidates is just bigger for companies, and it’ obvious that it would be.