Comparisons like this are not to be taken too seriously, because they always gloss over important factors. Comparing us with Japan, for example, is grossly distorted by the fact that the majority of Japan's population lives in high-rise blocks in cities. Of course it's economic to give them high speed broadband connections. The small proportion of the population living in outlying country districts are unlikely to have any broadband at all.
In the UK the impetus has always been on coverage, not speed, and for most purposes very high speed is not needed. Video on demand is just entertainment, and is far less important than the many serious purposes which can be served very well on slower connections.
So I don't feel depressed by that survey. They've looked at one aspect of broadband provision where we don't seem to stack up very well when compared with other developed countries, but they haven't looked at the whole picture.