For many communities, churches are the community centers/libraries/cultural centers. They preform functions identical to the organizations you mentioned - although they do other things as well.

Regarding demand, your sources indirectly say over 100 million Americans attend church regularly (“43% of Americans”). That’s a big number.

Regardless, the issue isn’t just demand, but supply.

The “market” for churches is extremely local.

If large number of Filipinos arrive in San Francisco, their demand for churches won’t be met by an excess of Southern Baptist churches in Dallas.

I understand that separation of Church and State. But creating schools, immunities centers, etc. is a function NGO civil society groups.

Groups like that have historically helped create Churches, especially for immigrant groups whose demand isn’t met by “native” churches.

Many historically Catholic parishes were created with support from Episcopal parishes.

Not for religious reasons, but because they recognized that the German/Irish immigrants benefited from them.

That dynamic hasn’t gone away, even if only 100 million Americans attend church regularly.