Honestly Japan being much more condensed it probably makes sense. In the US we're too spread out to abandon certain technologies yet. My parents still have (3Mbps) DLS as their only option. I have a brother who doesn't even have that. He uses he cell phone for all his internet browsing occasionally tethering it to a desktop.
I live in a town - a small town (population ~8,000), but still a town, and we have good cable modem speeds but only the newest neighborhoods have fiber available (the local telecom company has installed it in new developments since 2010 or so, but hasn't retrofitted any older subdivisions).