Superlative + of any + singular nominative

Here are three specimens from the web:

The City of New York serves as an enormous engine of United States and world’s economy. Its gross metropolitan product most of the time, is the largest of any city

The infrastructure of the town is growing at an unprecedented pace, making the town’s planning area the largest of any city or town in Baldwin County.

Article: Philadelphia Unifies Mental-Health Agencies; Budget Largest of Any City Agency.

I understand that paraphrasing these sentences to make them logical and grammatical, according to my lights, would be very difficult. We would not say:

It has the largest budget of Amarillo. It has the largest budget of Lubbock. It hass the largest budget of any city in Texas.

Can anyone lead me to a prescriptive grammarians' ruling? Wouldn't be better to use the possessive?

Budget largest of any city agency's