"If these types of operations were compelling financial projects, then you'd have a rush of entrepreneurs putting in these types of services," Balhoff said. "That's the nature of the capitalist system we're part of. The fact that you don't see any carrier-class entities or even entrepreneurs rushing into this space means you should beware."

Taxpayer risk?

Vos and other proponents say there is little risk to taxpayers for two reasons. First, Vos claimed that public networks would pay for themselves even if the only subscriber was the city.

"The cities plan to use the network not just for public access but also for their own purposes, like public safety," she said. "Any employee who goes out is more efficient and saves the city money if they're on a citywide network. They can check records or file forms without returning to the office -- that sort of thing. Public employees become more efficient and the cities can cancel T1 lines, which is one reason why the [incumbent telecoms] aren't happy."

Second, in most cities, the financial risk is being assumed by third parties, Vos said. For example, EarthLink Inc. is paying the cost of installing the wireless network in Philadelphia. EarthLink gains access to city-owned utility poles but is getting no direct subsidies from the city, Vos said.