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.