It would have to be a national mandate that is available in every city or everyone would use the free service from one city but not vote to raise the taxes in their city to pay for their own.
If it’s a national mandate, then might as well make it a national service.
That quickly becomes a tragedy of the commons. The city residents pay for it but how do you verify “citizenship”?
If every city has the same then why would you even want to?
It would have to be a national mandate that is available in every city or everyone would use the free service from one city but not vote to raise the taxes in their city to pay for their own.
If it’s a national mandate, then might as well make it a national service.