The only one to foot the bill were the cable providers.
true, in that the city didn't write a check, they did
subsidize the construction through reduced tax rates, a legal monopoly preventing competition, and ironclad contracts with the city. Sure, the city couldn't write a check for construction, but it sure as hell did sign long-term contracts to buy various services.
Remember, franchise agreements are made by the individual municipalities, local taxes cannot possibly fund a network.
Not directly, but there are MANY ways around that.
Poles are not usually owned by the municipality - the cablecos pay the phone or electric company for attachment.
Even back then, the poles were "public infrastructure" under the control of the Public Utility Commission. They were installed by the power company, but legally owned by the PUC. And the PUC regulates access, and sets (and collects) fees for attachment. (that's "the deal" for putting them on right-of-ways.)
Also, there is no monopoly guarantee of the franchise. Remember, exclusive agreements are illegal.
Yes there is, or was
as they're aren't legal anymore. If you really think the government doesn't hand out monopolies, try building your own power, water, or gas system. Hell, just try to build your own power generator (hydro, wind, or solar -- 'tho solar is getting easier) [for the record, my grandfather tried that 30+/- years ago... duke power created such a shit-storm of red-tape he abandoned the idea... a dam on a creek that would've made a few kWh. We got our revenge when they wanted to run a transmission line across the property.]