There are almost no places where a housing shortage is due to a lack of land. Housing shortages have all sorts of reasons, from constructions cost, to zoning, to restrictions on what can be built, but it's virtually never a lack of land.
And parking is a productive use - they have services once a week, and parking means people can come to the service. That's the definition of productive use. Something does not need to be used 24/7 to be productive.
Why should churches get great real estate in central locations but not housing? If people only come to church once a week, surely they can spend the extra time driving further.
Church goers using parking lots like this is a use, but I doubt it's a productive charitable use that should to be subsidized by localities.
Every other contemporary development in my area that faces real economic reality is ground floor retail, commercial/residential on top, and optionally underground parking.
There are certainly productive religious charitable efforts using facilities like this: homeless shelters, community low-cost/free clinics, soup kitchens. I think these uses should be tax subsidized, but other mystical efforts should not be whether they generate a profit or not.
I think a good reform to the 501c3 system would be to make non-profits like these churches and hospitals classify their actual charitable activity and separate it from their other activity, just like individuals with a mix of personal/small business income/expenses are required to do.