So the drivers were volunteers who worked for free? The diesel fuel was a free donation? The bus maintenance was done for free by good-hearted mechanics on their days off?
Tax dollars paid for this "free" service - as they always do. Politicians always take the credit for being kind with other people's money.
Of course the free bus fare was temporary.

Welcome 2024, good-bye free bus fares in Miami-Dade
The start of the new year brought many changes to Miami-Dade, including the end of the free bus fare program that started in November 2023.
www.nbcmiami.com
And there's a free transportation service in South Florida (that's not a bus) called Freebee.