So, if you have a quota (or a bonus) of diverse hires needed, you will either end up lowering your standards or spend a lot more money in order to fill the hiring needs.
Is the pool smaller because you primarily rely on referrals from your (already not especially diverse) workforce and applications from people off the street? Are you recruiting from universities that are predominantly white, as a result implicitly biasing your available pool of recent college graduates? Are you recruiting only from your local area, subjecting yourself to the local race balance?
If hiring diverse candidates costs more money, that can absolutely still be worth it if hiring diverse candidates provides measurable upsides. Of course, the cost matters - if it's 10x or 100x it's much harder to see a positive return. But dismissing it for being 'too hard' or 'too expensive' without actually doing an evaluation of the pros and cons is a little lazy, isn't it?
Fewer women in the Engineering workforce. Which stems from fewer women in College engineering programs. Which stems from (and I'm firmly in the "IMO" stage here) girls being encouraged to play with dolls and boys with legos.
Of course, engineering isn't the only occupation where there is an obvious gender bias, check out the book publishing industry. 90% white females, last I heard.
> Do you have data to support this?
The college numbers are broadly available, as are the employment records.
> citing any data here or personal experience working in HR or recruiting
Mostly from my attempts to hire someone for a number of positions - every time I get the candidate pool narrowed down to qualified individuals, they are all white males in their late 20's or early 30's. Is there an unconscious bias? Perhaps, but I'm narrowing based on their work experience, not their name, website or talking to them on the phone by this point.
> if hiring diverse candidates provides measurable upsides
It's very hard to quantify the benefit of a diverse work team. You know the benefits when you see them, but putting a dollar amount to it? "We made 20 fewer boneheaded decisions this year, resulting in a savings of $30,000." I'd love to see it, but I doubt I will.
Are there examples of business staffed by diverse staff that outperform boring white/asian male companies?