I disagree that it's "usually due more to corruption than anything else". I consider the problem one of accountability and politics (but not the corrupt type)... in the short term politicians are glad to have their names associated with grand projects -- building a new city-wide WiFi would be a boon, just as a new bridge, new bike paths, and other projects are. But long-term maintenance may get whittled away when the economy tanks, or due to other high priority budget concerns. As long as the politician can avoid disaster during their tenure there's no real incentive to provide adequate budget to these projects, and in fact there's a large disincentive as voters quite often push back against budget increases that aren't for their pet projects. The result is that politicians who can keep taxes low are re-elected but infrastructure budgets are stretched thin. None of that is necessarily corrupt, it's just short-sighted. Most cities "need" to replace their plumbing infrastructure, repair and replace roads and sidewalks, shore up levies, and at some point they'll need to upgrade internet infrastructure.
Here's some interesting reading on the topic that has specific examples across infrastructures (not a plug, I don't know these people): http://www.asce.org/failuretoact/
Consider the Comcast/Netflix issue... Comcast argued that other entities weren't upgrading their high-bandwidth lanes quickly enough for capacity to justify charging content providers extra money. How would that argument look if the entities were governments? Could you convince a municipality to spend money on a high-speed backbone when everyone appears to have working internet but experts see bottlenecks in the future, but when that budget must be split between roads and sewers and buses and...? Now that could become a corruption issue if, for example, an outgoing politician sees that an opponent from another party is going to win the next term; could they stack the budget to ensure a problem during their opponents term? Absolutely. But that isn't required for there to be problems.