The structures comprising the eruv, as well as its maintenance and upkeep, is funded by the organization constructing it in a particular location.
The public does not fund eruvin through taxation.
If the eruv makes use of structures (e.g. telephone poles used to affix wires or tubing), a fee may be assessed by the owner of the utility poles to the eruv association. Any costs associated with the eruv are paid directly by those who put up the eruv, not passed through to utility customers.