We are have ~15Mbps standard for cable and ~24Mbps for FiOS here in NYC suburbs. Optimum also has the 100Mbps service for $100, but I actually don't need that kind of speed.
Actually, most Americans aren't demanding that speed, and like everyone said, the rural areas of America make it hard to spread out high speed networks. We can do it, sure, but there seem to be higher priorities for spending for consumers and for government than bleeding edge speed right now. I think the pace at which broadband is being rolled out across the United States is acceptable, and if we want average speeds like Korea and Japan, we'd probably have to pay many times more. 
Politics definitely comes into play, and the telephone companies and cable companies would rather not spend their money on upgrading their networks, but there is progress being made, albeit with less haste than countries composed primarily of densely populated cities.