No the sums don't add up. Tax payers will subsidise some of the costs and Google will undoubtedly analyse the traffic to deliver yet even more personalised advertising. The local government will subsidise parts of the installation and make it legally as smooth as possible. Google will probably get cheaper offices or easier planning application processes, and who knows, they'll probably have some sway when it comes to local lawmaking, like any major contributing lobbyist...
... But in return Kansas City gets a bloody gigabit network for pittance. Free ADSL for anybody else.
It's practically unimaginable the services you could deliver to people with that sort of bandwidth because for a very long time it's been considered rude to assume anybody has anything faster than a 2Mbps connection. Google Fibre could stream 4k (with h.265). Even being able to assume the user has some upstream bandwidth for once is a complete boon to developers. In the UK the ratio is 10:1 almost everywhere unless you're on a business line (for four times the price) or the new FTTC options that are available in like 2% of the country.
tl;dr: you get a lot in exchange for letting Google in, not least that you will probably become the testing bed for all sorts of snazzy new technology. Stop moaning, pay your taxes and enjoy being able to watch all the porn at once.