It's definitely not a given even in big cities. In San Francisco the only places I've seen it offered are big apartment buildings with 50+ units. At least from what I've seen, even in pretty dense parts of the cities if you're in a small apartment building with like 10 units or you're in a duplex or attached SFH you can't get fiber service.

The upside is we can still get gigabit service over cable lines through comcast for a fairly reasonable price (although with terrible upload speeds, data caps on the plan, and the need to fight with support every year to prevent your price from going up, as with all comcast plans).