How about an Amazon warehouse?
But yeah, to your point, building more housing in a supply constricted market requires like way more proof.
Having lived in downtown San Francisco for 7 years now, I can’t help but notice how all the new highrises and fancy apartments have pushed down the prices of the normal stuff.
My current landlord tried to sell his house before we moved in and couldn’t get “enough” money for it because why pay $1,000,000 for a house from 1906 when you could pay the same for new construction across the street? Instead he had to settle for renting (to us). 3 years later and similar apartments in the area are now selling for $800,000 because there’s even more new construction around.
Rents are down too. Why pay $4000/mo to live in an old house when you can pay $4200/mo to live in a luxury highrise across the street?
Of course there are other metrics to consider than economic impact.
see also:
Those commercial and leisure entities you're talking about often push for these elements too, but they usually have to promise something in return, even so far as accepting clawback provisions and fines for failing to do so. Affordable Housing builders AFAIK never have these strings attached. If you'd counter to me with examples where this wasn't part of the agreement for commercial/leisure or where it was for affordable housing, I'd completely agree those are exceptions worth a closer look.
Or could be even easier to show that the lack of said units led to displacement for actual families.
I'm not saying it's easy peasy but if affordable unit advocates believe they are important then logically enforcing the regulations they fought for shouldn't be just shrugged off, at least as a signal to cities and developers.